Professor Somsak Panyakeow, D. Eng.
ศาสตราจารย์กิตติคุณ ดร.สมศักดิ์ ปัญญาแก้ว
Education
- D. Eng. (Electrical), Osaka University, Japan.1974
- M. Eng. (Electrical), Osaka University, Japan.1971
- B. Eng. (Electrical), Osaka University, Japan.1969
Email: Somsak.P@chula.ac.th
Research Interest
- Solar Cells and Photovoltaic Applications
- Laser Engineering
- Optoelectronics
- Quantum Devices and Nanoelectronics
Research Cluster
26.
Kanjanachuchai, S; Xu, M; Jaffré, A; Jittrong, A; Chokamnuai, T; Panyakeow, S; Boutchich, M
Excitation transfer in stacked quantum dot chains Journal Article
In: Semiconductor Science and Technology, vol. 30, no. 5, pp. 1-7, 2015, ISSN: 02681242, (cited By 3).
@article{Kanjanachuchai2015,
title = {Excitation transfer in stacked quantum dot chains},
author = {S Kanjanachuchai and M Xu and A Jaffré and A Jittrong and T Chokamnuai and S Panyakeow and M Boutchich},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928719302&doi=10.1088%2f0268-1242%2f30%2f5%2f055005&partnerID=40&md5=63eea598ef86420e5676800ca23f4780},
doi = {10.1088/0268-1242/30/5/055005},
issn = {02681242},
year = {2015},
date = {2015-01-01},
journal = {Semiconductor Science and Technology},
volume = {30},
number = {5},
pages = {1-7},
publisher = {Institute of Physics Publishing},
abstract = {Stacked InAs quantum dot chains (QDCs) on InGaAs/GaAs cross-hatch pattern (CHP) templates yield a rich emission spectrum with an unusual carrier transfer characteristic compared to conventional quantum dot (QD) stacks. The photoluminescent spectra of the controlled, single QDC layer comprise multiple peaks from the orthogonal QDCs, the free-standing QDs, the CHP, the wetting layers and the GaAs substrate. When the QDC layers are stacked, employing a 10 nm GaAs spacer between adjacent QDC layers, the PL spectra are dominated by the top-most stack, indicating that the QDC layers are nominally uncoupled. Under high excitation power densities when the high-energy peaks of the top stack are saturated, however, low-energy PL peaks from the bottom stacks emerge as a result of carrier transfers across the GaAs spacers. These unique PL signatures contrast with the state-filling effects in conventional, coupled QD stacks and serve as a means to quickly assess the presence of electronic coupling in stacks of dissimilar-sized nanostructures. © 2015 IOP Publishing Ltd.},
note = {cited By 3},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Stacked InAs quantum dot chains (QDCs) on InGaAs/GaAs cross-hatch pattern (CHP) templates yield a rich emission spectrum with an unusual carrier transfer characteristic compared to conventional quantum dot (QD) stacks. The photoluminescent spectra of the controlled, single QDC layer comprise multiple peaks from the orthogonal QDCs, the free-standing QDs, the CHP, the wetting layers and the GaAs substrate. When the QDC layers are stacked, employing a 10 nm GaAs spacer between adjacent QDC layers, the PL spectra are dominated by the top-most stack, indicating that the QDC layers are nominally uncoupled. Under high excitation power densities when the high-energy peaks of the top stack are saturated, however, low-energy PL peaks from the bottom stacks emerge as a result of carrier transfers across the GaAs spacers. These unique PL signatures contrast with the state-filling effects in conventional, coupled QD stacks and serve as a means to quickly assess the presence of electronic coupling in stacks of dissimilar-sized nanostructures. © 2015 IOP Publishing Ltd.
27.
Trisna, B A; Nakareseisoon, N; Eiwwongcharoen, W; Panyakeow, S; Kanjanachuchai, S
Reliable synthesis of self-running Ga droplets on GaAs (001) in MBE using RHEED patterns Journal Article
In: Nanoscale Research Letters, vol. 10, no. 1, 2015, ISSN: 19317573, (cited By 8).
@article{Trisna2015,
title = {Reliable synthesis of self-running Ga droplets on GaAs (001) in MBE using RHEED patterns},
author = {B A Trisna and N Nakareseisoon and W Eiwwongcharoen and S Panyakeow and S Kanjanachuchai},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84928331746&doi=10.1186%2fs11671-015-0890-7&partnerID=40&md5=c27d64decf9effac2fb6c8d19c9e598f},
doi = {10.1186/s11671-015-0890-7},
issn = {19317573},
year = {2015},
date = {2015-01-01},
journal = {Nanoscale Research Letters},
volume = {10},
number = {1},
publisher = {Springer New York LLC},
abstract = {Self-running Ga droplets on GaAs (001) surfaces are repeatedly and reliably formed in a molecular beam epitaxial (MBE) chamber despite the lack of real-time imaging capability of a low-energy electron microscope (LEEM) which has so far dominated the syntheses and studies of the running droplets phenomenon. Key to repeatability is the observation and registration of an appropriate reference point upon which subsequent sublimation conditions are based. The reference point is established using reflection high-energy electron diffraction (RHEED), not the noncongruent temperature used in LEEM where temperature discrepancies up to 25°C against MBE is measured. Our approach removes instrumental barriers to the observation and control of this complex dynamical system and may extend the usefulness of many droplet-related processes. © 2015, Trisna et al.; licensee Springer.},
note = {cited By 8},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Self-running Ga droplets on GaAs (001) surfaces are repeatedly and reliably formed in a molecular beam epitaxial (MBE) chamber despite the lack of real-time imaging capability of a low-energy electron microscope (LEEM) which has so far dominated the syntheses and studies of the running droplets phenomenon. Key to repeatability is the observation and registration of an appropriate reference point upon which subsequent sublimation conditions are based. The reference point is established using reflection high-energy electron diffraction (RHEED), not the noncongruent temperature used in LEEM where temperature discrepancies up to 25°C against MBE is measured. Our approach removes instrumental barriers to the observation and control of this complex dynamical system and may extend the usefulness of many droplet-related processes. © 2015, Trisna et al.; licensee Springer.
28.
Kunrugsa, M; Kiravittaya, S; Panyakeow, S; Ratanathammaphan, S
Effect of Ga deposition rates on GaSb nanostructures grown by droplet epitaxy Journal Article
In: Journal of Crystal Growth, vol. 402, pp. 285-290, 2014, ISSN: 00220248, (cited By 6).
@article{Kunrugsa2014a,
title = {Effect of Ga deposition rates on GaSb nanostructures grown by droplet epitaxy},
author = {M Kunrugsa and S Kiravittaya and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84917689862&doi=10.1016%2fj.jcrysgro.2014.06.036&partnerID=40&md5=582d93300d0ea83a9c3bca6e16e0218d},
doi = {10.1016/j.jcrysgro.2014.06.036},
issn = {00220248},
year = {2014},
date = {2014-01-01},
journal = {Journal of Crystal Growth},
volume = {402},
pages = {285-290},
publisher = {Elsevier},
abstract = {We investigate the effect of Ga deposition rates on GaSb nanostructures grown by droplet epitaxy on GaAs (001) substrates. Ga deposition rate was varied to form the different size and density of Ga droplets. After the droplets were exposed to Sb flux, not only the GaSb ring structure but also the complex nanostructure like the GaSb ring structure surrounded by ring-shaped dot molecules were obtained. A simple descriptive model is proposed to describe formation mechanisms of these nanostructures. It is found that Ga droplet size, distance between Ga droplets and diffusion area of Ga atoms during crystallization with Sb flux are all the crucial factors which determine the shape of GaSb nanostructures. Due to a lattice mismatch between GaSb and GaAs, strain occurred during a crystallization process should also be taken into account. Photoluminescence was carried out to verify our model. © 2014 Elsevier B.V.},
note = {cited By 6},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We investigate the effect of Ga deposition rates on GaSb nanostructures grown by droplet epitaxy on GaAs (001) substrates. Ga deposition rate was varied to form the different size and density of Ga droplets. After the droplets were exposed to Sb flux, not only the GaSb ring structure but also the complex nanostructure like the GaSb ring structure surrounded by ring-shaped dot molecules were obtained. A simple descriptive model is proposed to describe formation mechanisms of these nanostructures. It is found that Ga droplet size, distance between Ga droplets and diffusion area of Ga atoms during crystallization with Sb flux are all the crucial factors which determine the shape of GaSb nanostructures. Due to a lattice mismatch between GaSb and GaAs, strain occurred during a crystallization process should also be taken into account. Photoluminescence was carried out to verify our model. © 2014 Elsevier B.V.
29.
Kunrugsa, M; Kiravittaya, S; Sopitpan, S; Ratanathammaphan, S; Panyakeow, S
Molecular beam epitaxial growth of GaSb/GaAs quantum dots on Ge substrates Journal Article
In: Journal of Crystal Growth, vol. 401, pp. 441-444, 2014, ISSN: 00220248, (cited By 12).
@article{Kunrugsa2014,
title = {Molecular beam epitaxial growth of GaSb/GaAs quantum dots on Ge substrates},
author = {M Kunrugsa and S Kiravittaya and S Sopitpan and S Ratanathammaphan and S Panyakeow},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84906958887&doi=10.1016%2fj.jcrysgro.2014.02.048&partnerID=40&md5=8e717ba4bf17866659316fe19a1a3fcd},
doi = {10.1016/j.jcrysgro.2014.02.048},
issn = {00220248},
year = {2014},
date = {2014-01-01},
journal = {Journal of Crystal Growth},
volume = {401},
pages = {441-444},
publisher = {Elsevier B.V.},
abstract = {We perform structural and optical investigations of GaSb/GaAs quantum dots (QDs) grown on Ge (001) substrates by molecular beam epitaxy. Anti-phase domains (APDs) of GaAs are distributed on Ge substrate after the growth of GaAs due to the growth nature of III-V compound on group IV semiconductors having polar and non-polar behaviors. The APDs affect the QD growth as demonstrated by the growth of conventional InAs QDs on this surface. For GaSb QDs, the GaSb layer is grown on GaAs APD surface and compared with the GaSb layer on conventional (001) GaAs surface. Self-assembled QDs are formed on both surfaces but structural analysis reveals evidence of shape and size differences, which is attributed to the influence of the initial surface. Photoluminescence of GaSb/GaAs QDs grown on both Ge and GaAs substrates is studied. Emission from GaSb/GaAs QDs on Ge substrate can be detected till near room temperature (270 K). © 2014 Elsevier B.V.},
note = {cited By 12},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We perform structural and optical investigations of GaSb/GaAs quantum dots (QDs) grown on Ge (001) substrates by molecular beam epitaxy. Anti-phase domains (APDs) of GaAs are distributed on Ge substrate after the growth of GaAs due to the growth nature of III-V compound on group IV semiconductors having polar and non-polar behaviors. The APDs affect the QD growth as demonstrated by the growth of conventional InAs QDs on this surface. For GaSb QDs, the GaSb layer is grown on GaAs APD surface and compared with the GaSb layer on conventional (001) GaAs surface. Self-assembled QDs are formed on both surfaces but structural analysis reveals evidence of shape and size differences, which is attributed to the influence of the initial surface. Photoluminescence of GaSb/GaAs QDs grown on both Ge and GaAs substrates is studied. Emission from GaSb/GaAs QDs on Ge substrate can be detected till near room temperature (270 K). © 2014 Elsevier B.V.
30.
Pankaow, N; Prongjit, P; Thainoi, S; Panyakeow, S; Ratanathammaphan, S
Ring-to-dots transformation of InGaAs quantum rings grown by droplet epitaxy Journal Article
In: Microelectronic Engineering, vol. 110, pp. 298-301, 2013, ISSN: 01679317, (cited By 2).
@article{Pankaow2013,
title = {Ring-to-dots transformation of InGaAs quantum rings grown by droplet epitaxy},
author = {N Pankaow and P Prongjit and S Thainoi and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84885191160&doi=10.1016%2fj.mee.2013.02.029&partnerID=40&md5=a3b34ba727f05a7a30e396f82dd79ab2},
doi = {10.1016/j.mee.2013.02.029},
issn = {01679317},
year = {2013},
date = {2013-01-01},
journal = {Microelectronic Engineering},
volume = {110},
pages = {298-301},
publisher = {Elsevier B.V.},
abstract = {Post-growth annealing in UHV can lead to the deformation of crystallized nanostructures. Annealing effects on structural and optical properties of InGaAs quantum rings (QRs) grown by droplet epitaxy was examined. The InGaAs QRs were fabricated by depositing 3 monolayer (ML) of In0.5Ga0.5 on GaAs (100) at the substrate temperature of 140°C, and crystallized in As4 flux of∼7×10-6 Torr at 180°C for 5 min. After the crystallization, the substrate temperature was ramped up to the desired annealing temperature (Ta) of 300-400°C in As4 beam. In situ transformations of surface morphology were observed upon the evolution of RHEED patterns. Surface morphology was analyzed by AFM. As ramping up the annealing temperature, the QRs deformed and changed to numerous smaller QDs about the QR positions. Supposedly, there was segregation of group III atoms out of the QRs. At 380°C, the QRs properly lost their actual shapes and burst into high-density small QDs. Most possible reasons of the segregation can be crystalline instability of the low-temperature-crystallized QRs, along with the different surface kinetics of In and Ga atoms. © 2013 Elsevier B.V. All rights reserved.},
note = {cited By 2},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Post-growth annealing in UHV can lead to the deformation of crystallized nanostructures. Annealing effects on structural and optical properties of InGaAs quantum rings (QRs) grown by droplet epitaxy was examined. The InGaAs QRs were fabricated by depositing 3 monolayer (ML) of In0.5Ga0.5 on GaAs (100) at the substrate temperature of 140°C, and crystallized in As4 flux of∼7×10-6 Torr at 180°C for 5 min. After the crystallization, the substrate temperature was ramped up to the desired annealing temperature (Ta) of 300-400°C in As4 beam. In situ transformations of surface morphology were observed upon the evolution of RHEED patterns. Surface morphology was analyzed by AFM. As ramping up the annealing temperature, the QRs deformed and changed to numerous smaller QDs about the QR positions. Supposedly, there was segregation of group III atoms out of the QRs. At 380°C, the QRs properly lost their actual shapes and burst into high-density small QDs. Most possible reasons of the segregation can be crystalline instability of the low-temperature-crystallized QRs, along with the different surface kinetics of In and Ga atoms. © 2013 Elsevier B.V. All rights reserved.
31.
Boonpeng, P; Kiravittaya, S; Thainoi, S; Panyakeow, S; Ratanathammaphan, S
InGaAs quantum-dot-in-ring structure by droplet epitaxy Journal Article
In: Journal of Crystal Growth, vol. 378, pp. 435-438, 2013, ISSN: 00220248, (cited By 11).
@article{Boonpeng2013,
title = {InGaAs quantum-dot-in-ring structure by droplet epitaxy},
author = {P Boonpeng and S Kiravittaya and S Thainoi and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84885431768&doi=10.1016%2fj.jcrysgro.2012.12.056&partnerID=40&md5=626557246136c6375e9161a6971f0994},
doi = {10.1016/j.jcrysgro.2012.12.056},
issn = {00220248},
year = {2013},
date = {2013-01-01},
journal = {Journal of Crystal Growth},
volume = {378},
pages = {435-438},
publisher = {Elsevier B.V.},
abstract = {The controlled fabrication of self-assembled InGaAs nanostructures i.e., quantum ring (QR) and quantum-dot-in-ring (QDIR) by droplet epitaxy is reported. The effects of crystallization temperature (170-260 1°C) on the nanostructure shape, dimension, density, and depth profile are investigated. The QRs transform to QDIRs when the crystallization temperature is increased. At transformation state, the QRs with distorted nanohole profile along the [1-10] crystallographic direction are observed. The formation mechanism can be explained by the competitive crystallizations in and around the nanodroplet and strain relaxation in the nanohole. © 2013 Elsevier B.V. All rights reserved.},
note = {cited By 11},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The controlled fabrication of self-assembled InGaAs nanostructures i.e., quantum ring (QR) and quantum-dot-in-ring (QDIR) by droplet epitaxy is reported. The effects of crystallization temperature (170-260 1°C) on the nanostructure shape, dimension, density, and depth profile are investigated. The QRs transform to QDIRs when the crystallization temperature is increased. At transformation state, the QRs with distorted nanohole profile along the [1-10] crystallographic direction are observed. The formation mechanism can be explained by the competitive crystallizations in and around the nanodroplet and strain relaxation in the nanohole. © 2013 Elsevier B.V. All rights reserved.
32.
Han, S S; Higo, A; Yunpeng, W; Deura, M; Sugiyama, M; Nakano, Y; Panyakeow, S; Ratanathammaphan, S
In: Microelectronic Engineering, vol. 112, pp. 143-148, 2013, ISSN: 01679317, (cited By 1).
@article{Han2013,
title = {Effect of GaP and GaP/InGaP insertion layers on the structural and optical properties of InP quantum dots grown by metal-organic vapor phase epitaxy},
author = {S S Han and A Higo and W Yunpeng and M Deura and M Sugiyama and Y Nakano and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84884704307&doi=10.1016%2fj.mee.2013.01.026&partnerID=40&md5=817d6484f0e53058753d4b9f02045640},
doi = {10.1016/j.mee.2013.01.026},
issn = {01679317},
year = {2013},
date = {2013-01-01},
journal = {Microelectronic Engineering},
volume = {112},
pages = {143-148},
abstract = {A comparison of ultra-thin insertion layers (GaP and GaP/In 0.4Ga0.6P) on InP self-assembled quantum dots (SAQDs) grown on GaAs (0 0 1) substrates using metal-organic vapor phase epitaxy (MOVPE) was studied. Atomic force microscopy (AFM) and photoluminescence (PL) were employed to characterize the optical and structural properties of the grown InP QDs. It is found that the QD dimension, size distribution and density strongly depend on the insertion layer thickness which led to tune the emission wavelength and narrowing of full width at half maximum (FWHM) at low temperature (20-250 K) and at room-temperature PL measurements. This result is attributed to the improved QD size and quantum confinement effect arising from the insertion of the GaP and GaP/In0.4Ga0.6P layers. © 2013 Elsevier B.V. All rights reserved.},
note = {cited By 1},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A comparison of ultra-thin insertion layers (GaP and GaP/In 0.4Ga0.6P) on InP self-assembled quantum dots (SAQDs) grown on GaAs (0 0 1) substrates using metal-organic vapor phase epitaxy (MOVPE) was studied. Atomic force microscopy (AFM) and photoluminescence (PL) were employed to characterize the optical and structural properties of the grown InP QDs. It is found that the QD dimension, size distribution and density strongly depend on the insertion layer thickness which led to tune the emission wavelength and narrowing of full width at half maximum (FWHM) at low temperature (20-250 K) and at room-temperature PL measurements. This result is attributed to the improved QD size and quantum confinement effect arising from the insertion of the GaP and GaP/In0.4Ga0.6P layers. © 2013 Elsevier B.V. All rights reserved.
33.
Prongjit, P; Pankaow, N; Boonpeng, P; Thainoi, S; Panyakeow, S; Ratanathammaphan, S
Tensile strained, type II, GaP/GaAs nanostructures Journal Article
In: Chiang Mai Journal of Science, vol. 40, no. 6 SPEC. ISSUE 2, pp. 957-962, 2013, ISSN: 01252526, (cited By 0).
@article{Prongjit2013,
title = {Tensile strained, type II, GaP/GaAs nanostructures},
author = {P Prongjit and N Pankaow and P Boonpeng and S Thainoi and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84893497859&partnerID=40&md5=8a0a20a803ec1a1dcc4da7319eee129c},
issn = {01252526},
year = {2013},
date = {2013-01-01},
journal = {Chiang Mai Journal of Science},
volume = {40},
number = {6 SPEC. ISSUE 2},
pages = {957-962},
abstract = {We demonstrate the fabrication of self-assembled GaP nanostructures on GaAs (100) substrates by droplet epitaxy using molecular beam epitaxy. The dependency of GaP nanostructural properties on substrate temperature (250-350°C) as droplets are deposited is investigated. The dimension, density, and shape of GaP nanostructures strongly depend on the substrate temperature. It is found that nano-dots are formed when Ga droplets are deposited at 250°C, while ring-shape nanostructures are formed when Ga droplets are deposited at 300°C or higher. Photoluminescence results confirm the high quality of the GaP nanocrystals.},
note = {cited By 0},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We demonstrate the fabrication of self-assembled GaP nanostructures on GaAs (100) substrates by droplet epitaxy using molecular beam epitaxy. The dependency of GaP nanostructural properties on substrate temperature (250-350°C) as droplets are deposited is investigated. The dimension, density, and shape of GaP nanostructures strongly depend on the substrate temperature. It is found that nano-dots are formed when Ga droplets are deposited at 250°C, while ring-shape nanostructures are formed when Ga droplets are deposited at 300°C or higher. Photoluminescence results confirm the high quality of the GaP nanocrystals.
34.
Chokamnuai, T; Rattanadon, P; Thainoi, S; Panyakeow, S; Kanjanachuchai, S
Polarization anisotropy of stacked InAs quantum dots on InGaAs/GaAs cross-hatch patterns Journal Article
In: Journal of Crystal Growth, vol. 378, pp. 524-528, 2013, ISSN: 00220248, (cited By 5).
@article{Chokamnuai2013,
title = {Polarization anisotropy of stacked InAs quantum dots on InGaAs/GaAs cross-hatch patterns},
author = {T Chokamnuai and P Rattanadon and S Thainoi and S Panyakeow and S Kanjanachuchai},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84885430984&doi=10.1016%2fj.jcrysgro.2012.12.092&partnerID=40&md5=92820a3dd46bf1aca29f5fcb0319067f},
doi = {10.1016/j.jcrysgro.2012.12.092},
issn = {00220248},
year = {2013},
date = {2013-01-01},
journal = {Journal of Crystal Growth},
volume = {378},
pages = {524-528},
publisher = {Elsevier B.V.},
abstract = {Stacked InAs quantum dots (QDs) are grown on InGaAs/GaAs cross-hatch patterns (CHPs) by molecular beam epitaxy. The QDs, found almost exclusively on the cross-hatches, have greater lateral aspect ratio and are taller than typical QDs on flat surfaces. Polarization-resolved photoluminescent measurements show that both the QDs and CHPs exhibit polarization anisotropy. But while the CHP-related anisotropy is constant, the QD-related anisotropy is significantly enhanced or suppressed as the aspect ratio and height of the QD ensemble vary with the number of stacks. The polarization anisotropy observed agrees well with multiband tight-binding theoretical calculations of interband polarization in InAs/GaAs QDs. © 2013 Elsevier B.V. All rights reserved.},
note = {cited By 5},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Stacked InAs quantum dots (QDs) are grown on InGaAs/GaAs cross-hatch patterns (CHPs) by molecular beam epitaxy. The QDs, found almost exclusively on the cross-hatches, have greater lateral aspect ratio and are taller than typical QDs on flat surfaces. Polarization-resolved photoluminescent measurements show that both the QDs and CHPs exhibit polarization anisotropy. But while the CHP-related anisotropy is constant, the QD-related anisotropy is significantly enhanced or suppressed as the aspect ratio and height of the QD ensemble vary with the number of stacks. The polarization anisotropy observed agrees well with multiband tight-binding theoretical calculations of interband polarization in InAs/GaAs QDs. © 2013 Elsevier B.V. All rights reserved.
35.
Limwongse, T; Thainoi, S; Panyakeow, S; Kanjanachuchai, S
InGaAs quantum dots on cross-hatch patterns as a host for diluted magnetic semiconductor medium Journal Article
In: Journal of Nanomaterials, vol. 2013, 2013, ISSN: 16874110, (cited By 0).
@article{Limwongse2013,
title = {InGaAs quantum dots on cross-hatch patterns as a host for diluted magnetic semiconductor medium},
author = {T Limwongse and S Thainoi and S Panyakeow and S Kanjanachuchai},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84880221792&doi=10.1155%2f2013%2f791782&partnerID=40&md5=b4818669ae76f73ee16e2d7a026f65f6},
doi = {10.1155/2013/791782},
issn = {16874110},
year = {2013},
date = {2013-01-01},
journal = {Journal of Nanomaterials},
volume = {2013},
abstract = {Storage density on magnetic medium is increasing at an exponential rate. The magnetic region that stores one bit of information is correspondingly decreasing in size and will ultimately reach quantum dimensions. Magnetic quantum dots (QDs) can be grown using semiconductor as a host and magnetic constituents added to give them magnetic properties. Our results show how molecular beam epitaxy and, particularly, lattice-mismatched heteroepitaxy can be used to form laterally aligned, high-density semiconducting host in a single growth run without any use of lithography or etching. Representative results of how semiconductor QD hosts arrange themselves on various stripes and cross-hatch patterns are reported. © 2013 Teeravat Limwongse et al.},
note = {cited By 0},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Storage density on magnetic medium is increasing at an exponential rate. The magnetic region that stores one bit of information is correspondingly decreasing in size and will ultimately reach quantum dimensions. Magnetic quantum dots (QDs) can be grown using semiconductor as a host and magnetic constituents added to give them magnetic properties. Our results show how molecular beam epitaxy and, particularly, lattice-mismatched heteroepitaxy can be used to form laterally aligned, high-density semiconducting host in a single growth run without any use of lithography or etching. Representative results of how semiconductor QD hosts arrange themselves on various stripes and cross-hatch patterns are reported. © 2013 Teeravat Limwongse et al.
36.
Prongjit, P; Pankaow, N; Thainoi, S; Panyakeow, S; Ratanathammaphan, S
Formation of GaP nanostructures on GaAs (100) by droplet molecular beam epitaxy Journal Article
In: Physica Status Solidi (C) Current Topics in Solid State Physics, vol. 9, no. 7, pp. 1540-1542, 2012, ISSN: 18626351, (cited By 4).
@article{Prongjit2012,
title = {Formation of GaP nanostructures on GaAs (100) by droplet molecular beam epitaxy},
author = {P Prongjit and N Pankaow and S Thainoi and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84864021442&doi=10.1002%2fpssc.201100798&partnerID=40&md5=048297d24f58e66f74f0493f263b3555},
doi = {10.1002/pssc.201100798},
issn = {18626351},
year = {2012},
date = {2012-01-01},
journal = {Physica Status Solidi (C) Current Topics in Solid State Physics},
volume = {9},
number = {7},
pages = {1540-1542},
abstract = {In this contribution, we have demonstrated the fabrication of tensile strained GaP nanostructures on GaAs (100) substrates by droplet epitaxy using molecular beam epitaxy. The GaP nanostructures are ring-like structure due to crystallization with low P 2 pressure. The density of GaP ring-like nanostructures varies between 8.92×10 8-2.17×10 9 cm -2 and the average of diameter varies between 88.4-133 nm with increasing the Ga amount deposition in the range of 2.4-4.8 ML. The photoluminescence result shows the tensile strain-modified band gap effect of GaP nanostructure in GaAs matrix and it also confirms the high-quality of GaP nanocrystal. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.},
note = {cited By 4},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this contribution, we have demonstrated the fabrication of tensile strained GaP nanostructures on GaAs (100) substrates by droplet epitaxy using molecular beam epitaxy. The GaP nanostructures are ring-like structure due to crystallization with low P 2 pressure. The density of GaP ring-like nanostructures varies between 8.92×10 8-2.17×10 9 cm -2 and the average of diameter varies between 88.4-133 nm with increasing the Ga amount deposition in the range of 2.4-4.8 ML. The photoluminescence result shows the tensile strain-modified band gap effect of GaP nanostructure in GaAs matrix and it also confirms the high-quality of GaP nanocrystal. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
37.
Tangmettajittakul, O -A; Thainoi, S; Panyakeow, S; Ratanathammaphan, S
Evolution of self-assembled InAs quantum dot molecules by molecular beam epitaxy Journal Article
In: Physica Status Solidi (C) Current Topics in Solid State Physics, vol. 9, no. 7, pp. 1534-1536, 2012, ISSN: 18626351, (cited By 1).
@article{Tangmettajittakul2012,
title = {Evolution of self-assembled InAs quantum dot molecules by molecular beam epitaxy},
author = {O -A Tangmettajittakul and S Thainoi and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84864019137&doi=10.1002%2fpssc.201100620&partnerID=40&md5=74161472a731b022276f75c6a81fe121},
doi = {10.1002/pssc.201100620},
issn = {18626351},
year = {2012},
date = {2012-01-01},
journal = {Physica Status Solidi (C) Current Topics in Solid State Physics},
volume = {9},
number = {7},
pages = {1534-1536},
abstract = {Self-assembled InAs quantum dot molecules (QDMs) have been grown by thin-capping-and-regrowth MBE technique. The QDM-forming conditions have been changed by varying InAs growth rate in the range of 0.01-0.03 ML/s. We found that the InAs growth rate affects nano-propeller shape, dot density, and dot height. The densities of QDs, nano-propellers, and QDMs are increasing while increasing the InAs growth rate. In contrast, the dot height and the length of propeller blades are contrary to growth rate. Also, the uniformity of dots in QDMs can be changed by an increase of growth rate. These results are confirmed by photoluminescence (PL) measurement. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.},
note = {cited By 1},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Self-assembled InAs quantum dot molecules (QDMs) have been grown by thin-capping-and-regrowth MBE technique. The QDM-forming conditions have been changed by varying InAs growth rate in the range of 0.01-0.03 ML/s. We found that the InAs growth rate affects nano-propeller shape, dot density, and dot height. The densities of QDs, nano-propellers, and QDMs are increasing while increasing the InAs growth rate. In contrast, the dot height and the length of propeller blades are contrary to growth rate. Also, the uniformity of dots in QDMs can be changed by an increase of growth rate. These results are confirmed by photoluminescence (PL) measurement. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
38.
Han, S S; Panyakeow, S; Ratanathammaphan, S; Higo, A; Yunpeng, W; Deura, M; Sugiyama, M; Nakano, Y
The effect of thin gap insertion layer on InP nanostructure grown by metal-organic vapour phase epitaxys Journal Article
In: Canadian Journal of Chemical Engineering, vol. 90, no. 4, pp. 915-918, 2012, ISSN: 00084034, (cited By 0).
@article{Han2012,
title = {The effect of thin gap insertion layer on InP nanostructure grown by metal-organic vapour phase epitaxys},
author = {S S Han and S Panyakeow and S Ratanathammaphan and A Higo and W Yunpeng and M Deura and M Sugiyama and Y Nakano},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84863538558&doi=10.1002%2fcjce.21648&partnerID=40&md5=7b4fdb2489318892cd05cfe9f5f0a66f},
doi = {10.1002/cjce.21648},
issn = {00084034},
year = {2012},
date = {2012-01-01},
journal = {Canadian Journal of Chemical Engineering},
volume = {90},
number = {4},
pages = {915-918},
abstract = {The effect of thin GaP insertion layers on the structural and optical properties of InP/In 0.49Ga 0.51P self-assembled quantum dots (SAQDs) on GaAs (001) substrate grown by metal-organic vapour phase epitaxy has been reported. The properties of InP/In 0.49Ga 0.51P SAQDs are modified when a thin (1-4 ML) GaP layer is inserted underneath the InP quantum dots (QDs). Deposition of the GaP insertion layer affects the dot dimension and improves the size uniformity. The density, dimension and uniformity of InP QDs strongly depend on the GaP insertion layer thickness. This variation in QD size is a result of a material nucleation effect caused by atomic intermixing between the InP QDs and underlying GaP insertion layer and surface energy. The insertion of GaP layer led to tuning the emission wavelength and narrowing of full width at half maximum (FWHM) when they are characterised by PL measurements at room temperature. © 2012 Canadian Society for Chemical Engineering.},
note = {cited By 0},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The effect of thin GaP insertion layers on the structural and optical properties of InP/In 0.49Ga 0.51P self-assembled quantum dots (SAQDs) on GaAs (001) substrate grown by metal-organic vapour phase epitaxy has been reported. The properties of InP/In 0.49Ga 0.51P SAQDs are modified when a thin (1-4 ML) GaP layer is inserted underneath the InP quantum dots (QDs). Deposition of the GaP insertion layer affects the dot dimension and improves the size uniformity. The density, dimension and uniformity of InP QDs strongly depend on the GaP insertion layer thickness. This variation in QD size is a result of a material nucleation effect caused by atomic intermixing between the InP QDs and underlying GaP insertion layer and surface energy. The insertion of GaP layer led to tuning the emission wavelength and narrowing of full width at half maximum (FWHM) when they are characterised by PL measurements at room temperature. © 2012 Canadian Society for Chemical Engineering.
39.
Patanasemakul, N; Panyakeow, S; Kanjanachuchai, S
Chirped IngaAs quantum dot molecules for broadband applications Journal Article
In: Nanoscale Research Letters, vol. 7, 2012, ISSN: 19317573, (cited By 1).
@article{Patanasemakul2012,
title = {Chirped IngaAs quantum dot molecules for broadband applications},
author = {N Patanasemakul and S Panyakeow and S Kanjanachuchai},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84860674429&doi=10.1186%2f1556-276X-7-207&partnerID=40&md5=c82f9bbedf6bd6b64618cade4af402b0},
doi = {10.1186/1556-276X-7-207},
issn = {19317573},
year = {2012},
date = {2012-01-01},
journal = {Nanoscale Research Letters},
volume = {7},
publisher = {Springer New York LLC},
abstract = {Lateral InGaAs quantum dot molecules (QDMs) formed by partial-cap and regrowth technique exhibit two ground-state (GS) peaks controllable via the thicknesses of InAs seed quantum dots (x), GaAs cap (y), and InAs regrowth (z). By adjusting x/y/z in a stacked QDM bilayer, the GS peaks from the two layers can be offset to straddle, stagger, or join up with each other, resulting in multi-GS or broadband spectra. A non-optimized QDM bilayer with a 170-meV full-width at half-maximum is demonstrated. The temperature dependencies of the emission peak energies and intensities from the chirped QDM bilayers are well explained by Varshni's equation and thermal activation of carriers out of constituent quantum dots. © 2012 Patanasemakul et al.},
note = {cited By 1},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Lateral InGaAs quantum dot molecules (QDMs) formed by partial-cap and regrowth technique exhibit two ground-state (GS) peaks controllable via the thicknesses of InAs seed quantum dots (x), GaAs cap (y), and InAs regrowth (z). By adjusting x/y/z in a stacked QDM bilayer, the GS peaks from the two layers can be offset to straddle, stagger, or join up with each other, resulting in multi-GS or broadband spectra. A non-optimized QDM bilayer with a 170-meV full-width at half-maximum is demonstrated. The temperature dependencies of the emission peak energies and intensities from the chirped QDM bilayers are well explained by Varshni's equation and thermal activation of carriers out of constituent quantum dots. © 2012 Patanasemakul et al.
40.
Boonpeng, P; Jevasuwan, W; Nuntawong, N; Thainoi, S; Panyakeow, S; Ratanathammaphan, S
Transformation of concentric quantum double rings to single quantum rings with squarelike nanoholes on GaAs(0 0 1) by droplet epitaxy Journal Article
In: Journal of Crystal Growth, vol. 323, no. 1, pp. 271-274, 2011, ISSN: 00220248, (cited By 4).
@article{Boonpeng2011,
title = {Transformation of concentric quantum double rings to single quantum rings with squarelike nanoholes on GaAs(0 0 1) by droplet epitaxy},
author = {P Boonpeng and W Jevasuwan and N Nuntawong and S Thainoi and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79957985814&doi=10.1016%2fj.jcrysgro.2010.12.034&partnerID=40&md5=0313280f95279ff610a5b4f02f431f17},
doi = {10.1016/j.jcrysgro.2010.12.034},
issn = {00220248},
year = {2011},
date = {2011-01-01},
journal = {Journal of Crystal Growth},
volume = {323},
number = {1},
pages = {271-274},
abstract = {The fabrication of self-assembled InxGa1-xAs nanostructures on GaAs(0 0 1) substrates grown by droplet epitaxy using molecular beam epitaxy is reported. The effect of In contents (0≤x≤0.2) for InxGa1-x droplets on their shape, dimension, density, and depth profile was investigated. The concentric quantum double rings (CQDRs) are transformed into quantum rings (QRs) with squarelike nanoholes when In content is increased. The transformation mechanism is explained by the strain relaxation arguments. As In content increases, crystallization can occur not only from the outer periphery, but also from the inner periphery of the rings. This is confirmed by decrease in outer dimension and change in the hole profile along the [1 -1 0] direction. In addition, low density QRs with shallow nanoholes were found on the surface for In content of 0.2. The surface morphology of InxGa1-xAs nanostructures was examined by atomic force microscopy (AFM). © 2010 Elsevier B.V. All rights reserved.},
note = {cited By 4},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The fabrication of self-assembled InxGa1-xAs nanostructures on GaAs(0 0 1) substrates grown by droplet epitaxy using molecular beam epitaxy is reported. The effect of In contents (0≤x≤0.2) for InxGa1-x droplets on their shape, dimension, density, and depth profile was investigated. The concentric quantum double rings (CQDRs) are transformed into quantum rings (QRs) with squarelike nanoholes when In content is increased. The transformation mechanism is explained by the strain relaxation arguments. As In content increases, crystallization can occur not only from the outer periphery, but also from the inner periphery of the rings. This is confirmed by decrease in outer dimension and change in the hole profile along the [1 -1 0] direction. In addition, low density QRs with shallow nanoholes were found on the surface for In content of 0.2. The surface morphology of InxGa1-xAs nanostructures was examined by atomic force microscopy (AFM). © 2010 Elsevier B.V. All rights reserved.
41.
Jevasuwan, W; Boonpeng, P; Thainoi, S; Panyakeow, S; Ratanathammaphan, S
InP ring-shaped quantum-dot molecules grown by droplet molecular beam epitaxy Journal Article
In: Journal of Crystal Growth, vol. 323, no. 1, pp. 275-278, 2011, ISSN: 00220248, (cited By 7).
@article{Jevasuwan2011,
title = {InP ring-shaped quantum-dot molecules grown by droplet molecular beam epitaxy},
author = {W Jevasuwan and P Boonpeng and S Thainoi and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79958002371&doi=10.1016%2fj.jcrysgro.2010.11.135&partnerID=40&md5=50b266c6eb2083055e155f39441d86ac},
doi = {10.1016/j.jcrysgro.2010.11.135},
issn = {00220248},
year = {2011},
date = {2011-01-01},
journal = {Journal of Crystal Growth},
volume = {323},
number = {1},
pages = {275-278},
abstract = {In this paper, the reflection high energy electron diffraction of the transition from a two-dimensional growth mode to a three-dimensional growth mode of InP ring-shaped quantum-dot molecule (QDM) formation in the matrices of In0.5Ga0.5P on semi-insulating GaAs(0 0 1) substrates was reported. All samples were grown by solid-source molecular beam epitaxy using the droplet epitaxy technique under different crystallization temperature conditions. The surface morphologies of InP ring-shaped QDMs were examined by atomic force microscopy and the photoluminescence (PL) spectra were obtained by the 478 nm line of an Ar laser with an InGaAs detector. The dependence of the PL ground-state peak energies as the function of power and temperature with the tendencies of PL peak and full width at half maximum were investigated and discussed. © 2010 Elsevier B.V. All rights reserved.},
note = {cited By 7},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this paper, the reflection high energy electron diffraction of the transition from a two-dimensional growth mode to a three-dimensional growth mode of InP ring-shaped quantum-dot molecule (QDM) formation in the matrices of In0.5Ga0.5P on semi-insulating GaAs(0 0 1) substrates was reported. All samples were grown by solid-source molecular beam epitaxy using the droplet epitaxy technique under different crystallization temperature conditions. The surface morphologies of InP ring-shaped QDMs were examined by atomic force microscopy and the photoluminescence (PL) spectra were obtained by the 478 nm line of an Ar laser with an InGaAs detector. The dependence of the PL ground-state peak energies as the function of power and temperature with the tendencies of PL peak and full width at half maximum were investigated and discussed. © 2010 Elsevier B.V. All rights reserved.
42.
Pankaow, N; Thainoi, S; Panyakeow, S; Ratanathammaphan, S
Surface morphology and photoluminescence of InGaAs quantum rings grown by droplet epitaxy with varying In0.5Ga0.5 droplet amount Journal Article
In: Journal of Crystal Growth, vol. 323, no. 1, pp. 282-285, 2011, ISSN: 00220248, (cited By 7).
@article{Pankaow2011a,
title = {Surface morphology and photoluminescence of InGaAs quantum rings grown by droplet epitaxy with varying In0.5Ga0.5 droplet amount},
author = {N Pankaow and S Thainoi and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79957981518&doi=10.1016%2fj.jcrysgro.2010.10.129&partnerID=40&md5=18d7b05133f3bdc84f729b941bfbe281},
doi = {10.1016/j.jcrysgro.2010.10.129},
issn = {00220248},
year = {2011},
date = {2011-01-01},
journal = {Journal of Crystal Growth},
volume = {323},
number = {1},
pages = {282-285},
abstract = {We have presented the study result of physical and optical properties of the InGaAs quantum ring (QR) structures grown by droplet epitaxy using molecular beam epixaty. The structural properties and quality of QRs strongly depended on In0.5Ga0.5 droplet amount. The photoluminescence (PL) results confirmed the crystal quality of the nanocrystal of the capped samples with the optimum In0.5Ga0.5 droplet amount. The optimum In0.5Ga0.5 amount is 3 and 4 ML (monolayer) under the droplet forming condition of 210°C substrate and crystallization at 180°C. The PL measuring parameters, including excitation intensity and polarization, have been varied. The polarized PL spectra indicated anisotropy in the QR structures. © 2010 Elsevier B.V. All rights reserved.},
note = {cited By 7},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We have presented the study result of physical and optical properties of the InGaAs quantum ring (QR) structures grown by droplet epitaxy using molecular beam epixaty. The structural properties and quality of QRs strongly depended on In0.5Ga0.5 droplet amount. The photoluminescence (PL) results confirmed the crystal quality of the nanocrystal of the capped samples with the optimum In0.5Ga0.5 droplet amount. The optimum In0.5Ga0.5 amount is 3 and 4 ML (monolayer) under the droplet forming condition of 210°C substrate and crystallization at 180°C. The PL measuring parameters, including excitation intensity and polarization, have been varied. The polarized PL spectra indicated anisotropy in the QR structures. © 2010 Elsevier B.V. All rights reserved.
43.
Tantiweerasophon, W; Thainoi, S; Changmuang, P; Kanjanachuchai, S; Rattanathammaphan, S; Panyakeow, S
Self-assembled InAs quantum dots on anti-phase domains of GaAs on Ge substrates Journal Article
In: Journal of Crystal Growth, vol. 323, no. 1, pp. 254-258, 2011, ISSN: 00220248, (cited By 7).
@article{Tantiweerasophon2011,
title = {Self-assembled InAs quantum dots on anti-phase domains of GaAs on Ge substrates},
author = {W Tantiweerasophon and S Thainoi and P Changmuang and S Kanjanachuchai and S Rattanathammaphan and S Panyakeow},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79957982711&doi=10.1016%2fj.jcrysgro.2010.12.083&partnerID=40&md5=98f411eae4dca644ea45c27da833888f},
doi = {10.1016/j.jcrysgro.2010.12.083},
issn = {00220248},
year = {2011},
date = {2011-01-01},
journal = {Journal of Crystal Growth},
volume = {323},
number = {1},
pages = {254-258},
abstract = {The authors report the formation of self-assembled InAs quantum dots (QDs) grown on GaAs/Ge substrates having anti-phase domains (APDs) by molecular beam epitaxy. The AFM images of InAs QDs grown on different GaAs thicknesses are shown and compared. The samples with InAs coverage of 1.80 MLs with GaAs thickness of 300 and 700 nm show non-uniformed size distribution of the dots. Due to anisotropic property of quantum dots, ellipsoidal quantum dots appear. Unexpectedly, most of InAs quantum dots align perpendicularly to anti-phase boundary (APB) and to quantum dot alignment formed in adjacent domains. Photoluminescence spectrum excited by 20 mW 476-nm Ar laser at 20 K does not show emission peak of InAs QDs. This is due to defects in the GaAs buffer layer. © 2010 Elsevier B.V. All rights reserved.},
note = {cited By 7},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The authors report the formation of self-assembled InAs quantum dots (QDs) grown on GaAs/Ge substrates having anti-phase domains (APDs) by molecular beam epitaxy. The AFM images of InAs QDs grown on different GaAs thicknesses are shown and compared. The samples with InAs coverage of 1.80 MLs with GaAs thickness of 300 and 700 nm show non-uniformed size distribution of the dots. Due to anisotropic property of quantum dots, ellipsoidal quantum dots appear. Unexpectedly, most of InAs quantum dots align perpendicularly to anti-phase boundary (APB) and to quantum dot alignment formed in adjacent domains. Photoluminescence spectrum excited by 20 mW 476-nm Ar laser at 20 K does not show emission peak of InAs QDs. This is due to defects in the GaAs buffer layer. © 2010 Elsevier B.V. All rights reserved.
44.
Thongkamkoon, N; Patanasemakul, N; Siripitakchai, N; Thainoi, S; Panyakeow, S; Kanjanachuchai, S
Bimodal optical characteristics of lateral InGaAs quantum dot molecules Journal Article
In: Journal of Crystal Growth, vol. 323, no. 1, pp. 206-210, 2011, ISSN: 00220248, (cited By 3).
@article{Thongkamkoon2011,
title = {Bimodal optical characteristics of lateral InGaAs quantum dot molecules},
author = {N Thongkamkoon and N Patanasemakul and N Siripitakchai and S Thainoi and S Panyakeow and S Kanjanachuchai},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79958010018&doi=10.1016%2fj.jcrysgro.2010.11.104&partnerID=40&md5=3b0e0cf317bc0e8265534034d9ed041d},
doi = {10.1016/j.jcrysgro.2010.11.104},
issn = {00220248},
year = {2011},
date = {2011-01-01},
journal = {Journal of Crystal Growth},
volume = {323},
number = {1},
pages = {206-210},
abstract = {Lateral InGaAs quantum dot molecules (QDMs) formed by thin-cap-and-regrowth molecular beam epitaxial technique comprise large, central quantum dots (cQDs) and small, satellite quantum dots (sQDs) in close proximity. Temperature-dependent photoluminescent (PL) measurements show that the bimodal size distribution gives rise to bimodal optical characteristics: the cQDs ground-state (GS) emissions vary slowly with temperature while the full-width at half maximum (FWHM) remains almost constant; the sQDs GS emissions, on the other hand, exhibit a sigmoidal temperature shift while the FWHM shows an anomalous temperature behaviour. The bimodal optical characteristics are well described in the existing framework of spatially localised excitons in QDs and inter- and intramolecular carrier redistributions in each and among the QDMs via non-resonant multi-phonon assisted mechanisms. © 2010 Elsevier B.V. All rights reserved.},
note = {cited By 3},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Lateral InGaAs quantum dot molecules (QDMs) formed by thin-cap-and-regrowth molecular beam epitaxial technique comprise large, central quantum dots (cQDs) and small, satellite quantum dots (sQDs) in close proximity. Temperature-dependent photoluminescent (PL) measurements show that the bimodal size distribution gives rise to bimodal optical characteristics: the cQDs ground-state (GS) emissions vary slowly with temperature while the full-width at half maximum (FWHM) remains almost constant; the sQDs GS emissions, on the other hand, exhibit a sigmoidal temperature shift while the FWHM shows an anomalous temperature behaviour. The bimodal optical characteristics are well described in the existing framework of spatially localised excitons in QDs and inter- and intramolecular carrier redistributions in each and among the QDMs via non-resonant multi-phonon assisted mechanisms. © 2010 Elsevier B.V. All rights reserved.
45.
Himwas, C; Panyakeow, S; Kanjanachuchai, S
Optical properties of as-grown and annealed InAs quantum dots on InGaAs cross-hatch patterns Journal Article
In: Nanoscale Research Letters, vol. 6, pp. 1-7, 2011, ISSN: 19317573, (cited By 6).
@article{Himwas2011a,
title = {Optical properties of as-grown and annealed InAs quantum dots on InGaAs cross-hatch patterns},
author = {C Himwas and S Panyakeow and S Kanjanachuchai},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84856034404&doi=10.1186%2f1556-276X-6-496&partnerID=40&md5=37fb67393561d945fb6c2d8975b9016f},
doi = {10.1186/1556-276X-6-496},
issn = {19317573},
year = {2011},
date = {2011-01-01},
journal = {Nanoscale Research Letters},
volume = {6},
pages = {1-7},
abstract = {InAs quantum dots (QDs) grown on InGaAs cross-hatch pattern (CHP) by molecular beam epitaxy are characterized by photoluminescence (PL) at 20 K. In contrast to QDs grown on flat GaAs substrates, those grown on CHPs exhibit rich optical features which comprise as many as five ground-state emissions from [1-10]- and [110]-aligned QDs, two wetting layers (WLs), and the CHP. When subject to in situ annealing at 700°C, the PL signals rapidly degrades due to the deterioration of the CHP which sets the upper limit of overgrowth temperature. Ex situ hydrogen annealing at a much lower temperature of 350°C, however, results in an overall PL intensity increase with a significant narrowing and a small blueshift of the high-energy WL emission due to hydrogen bonding which neutralizes defects and relieves associated strains. © 2011 Himwas et al.},
note = {cited By 6},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
InAs quantum dots (QDs) grown on InGaAs cross-hatch pattern (CHP) by molecular beam epitaxy are characterized by photoluminescence (PL) at 20 K. In contrast to QDs grown on flat GaAs substrates, those grown on CHPs exhibit rich optical features which comprise as many as five ground-state emissions from [1-10]- and [110]-aligned QDs, two wetting layers (WLs), and the CHP. When subject to in situ annealing at 700°C, the PL signals rapidly degrades due to the deterioration of the CHP which sets the upper limit of overgrowth temperature. Ex situ hydrogen annealing at a much lower temperature of 350°C, however, results in an overall PL intensity increase with a significant narrowing and a small blueshift of the high-energy WL emission due to hydrogen bonding which neutralizes defects and relieves associated strains. © 2011 Himwas et al.
46.
Boonpeng, P; Jevasuwan, W; Panyakeow, S; Ratanathammaphan, S
Fabrication of self-assembled InGaAs squarelike nanoholes on GaAs(001) by droplet epitaxy Journal Article
In: Japanese Journal of Applied Physics, vol. 49, no. 4 PART 2, 2010, ISSN: 00214922, (cited By 3).
@article{Boonpeng2010,
title = {Fabrication of self-assembled InGaAs squarelike nanoholes on GaAs(001) by droplet epitaxy},
author = {P Boonpeng and W Jevasuwan and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-77952738153&doi=10.1143%2fJJAP.49.04DH09&partnerID=40&md5=711c47bed53f01d59b03ceff8ebed1b1},
doi = {10.1143/JJAP.49.04DH09},
issn = {00214922},
year = {2010},
date = {2010-01-01},
journal = {Japanese Journal of Applied Physics},
volume = {49},
number = {4 PART 2},
abstract = {The fabrication of self-assembled InGaAs squarelike nanoholes on GaAs(001) substrates grown by droplet epitaxy using molecular beam epitaxy was reported. The formation mechanism is explained by the As4 diffusion in droplets during the supply of As4 flux. The effects of substrate temperature (300-390 °C) during the InGa droplet deposition on their dimension and density were investigated. The surface morphology of InGaAs nanoholes as well as their depth profile was examined by atomic force microscopy (AFM). The square shape is oriented along [110] and [1̄10] crystallographic directions with slightly different profiles due to anisotropy behavior. The size uniformity of the squarelike nanoholes is well controlled with less deviation at higher substrate temperatures. © 2010 The Japan Society of Applied Physics.},
note = {cited By 3},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The fabrication of self-assembled InGaAs squarelike nanoholes on GaAs(001) substrates grown by droplet epitaxy using molecular beam epitaxy was reported. The formation mechanism is explained by the As4 diffusion in droplets during the supply of As4 flux. The effects of substrate temperature (300-390 °C) during the InGa droplet deposition on their dimension and density were investigated. The surface morphology of InGaAs nanoholes as well as their depth profile was examined by atomic force microscopy (AFM). The square shape is oriented along [110] and [1̄10] crystallographic directions with slightly different profiles due to anisotropy behavior. The size uniformity of the squarelike nanoholes is well controlled with less deviation at higher substrate temperatures. © 2010 The Japan Society of Applied Physics.
47.
Jevasuwan, W; Boonpeng, P; Panyakeow, S; Ratanathammaphan, S
Growth and characterization of InP ringlike quantum-dot molecules grown by solid-source molecular beam epitaxy Journal Article
In: Journal of Nanoscience and Nanotechnology, vol. 10, no. 11, pp. 7291-7294, 2010, ISSN: 15334880, (cited By 2).
@article{Jevasuwan2010,
title = {Growth and characterization of InP ringlike quantum-dot molecules grown by solid-source molecular beam epitaxy},
author = {W Jevasuwan and P Boonpeng and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79955539061&doi=10.1166%2fjnn.2010.2860&partnerID=40&md5=74402e6521930ab80bbfa80da60ce780},
doi = {10.1166/jnn.2010.2860},
issn = {15334880},
year = {2010},
date = {2010-01-01},
journal = {Journal of Nanoscience and Nanotechnology},
volume = {10},
number = {11},
pages = {7291-7294},
abstract = {In this paper, we have studied the fabrication of lnP ringlike quantum-dot molecules on GaAs(001) substrate grown by solid-source molecular beam epitaxy using droplet epitaxy technique and the effect of In deposition rate on the physical and optical properties of lnP ringlike quantum-dot molecules. The In deposition rate is varied from 0.2 MLJs to 0.4, 0.8 and 1.6 MLJ5. The surface morphology and cross-section were examined by ox-situ atomic force microscope and transmission electron microscope, respectively. The increasing of In deposition rate results in the decreasing of outer and inner diameters of lnP ringlike quantum-dot molecules and height of lnP quantum dots but increases the InP quantum dot and ringlike quantum-dot molecule densities. The photoluminescence peaks of lnP ringlike quantum-dot molecules are blue-shifted and FWHM is narrower when In deposition rate is bigger. Copyright © 2010 American Scientific Publishers.},
note = {cited By 2},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In this paper, we have studied the fabrication of lnP ringlike quantum-dot molecules on GaAs(001) substrate grown by solid-source molecular beam epitaxy using droplet epitaxy technique and the effect of In deposition rate on the physical and optical properties of lnP ringlike quantum-dot molecules. The In deposition rate is varied from 0.2 MLJs to 0.4, 0.8 and 1.6 MLJ5. The surface morphology and cross-section were examined by ox-situ atomic force microscope and transmission electron microscope, respectively. The increasing of In deposition rate results in the decreasing of outer and inner diameters of lnP ringlike quantum-dot molecules and height of lnP quantum dots but increases the InP quantum dot and ringlike quantum-dot molecule densities. The photoluminescence peaks of lnP ringlike quantum-dot molecules are blue-shifted and FWHM is narrower when In deposition rate is bigger. Copyright © 2010 American Scientific Publishers.
48.
Panyakeow, S
Quadra-quantum dots and related patterns of quantum dot molecules: Basic nanostructures for quantum dot cellular automata application Journal Article
In: Engineering Journal, vol. 14, no. 4, pp. 41-56, 2010, ISSN: 01258281, (cited By 0).
@article{Panyakeow2010,
title = {Quadra-quantum dots and related patterns of quantum dot molecules: Basic nanostructures for quantum dot cellular automata application},
author = {S Panyakeow},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79960752510&doi=10.4186%2fej.2010.14.4.41&partnerID=40&md5=a6ef335393f1f345c48ad0031e6a8451},
doi = {10.4186/ej.2010.14.4.41},
issn = {01258281},
year = {2010},
date = {2010-01-01},
journal = {Engineering Journal},
volume = {14},
number = {4},
pages = {41-56},
abstract = {Laterally close-packed quantum dots (QDs) called quantum dot molecules (QDMs) are grown using a modified molecular beam epitaxy (MBE) method. Quantum dots may be aligned and cross hatched. Quantum rings (QRs) created from quantum dot transformation during thin or partial capping are used as templates for the formations of bi-quantum dot molecules (Bi-QDMs) and quantum dot rings (QDRs). The preferable quantum dot nanostructure for quantum computation based on quantum dot cellular automata (QCA) is laterally close-packed quantum dot molecules having four quantum dots at the corners of square configuration. These four quantum dot sets are called quadra-quantum dots (QQDs). Aligned quadra-quantum dots with two electron confinements work like a wire for digital information transmission using the Coulomb repulsion force, which is fast and consumes little power. A combination of quadra-quantum dots in line and cross-over works as logic gates and memory bits. A molecular Beam Epitaxial growth technique called "Droplet Epitaxy" has been developed for several quantum nanostructures such as quantum rings and quantum dot rings. Quantum rings are prepared by using 20 ML In-Ga (15:85) droplets deposited on a GaAs substrate at 390°C with a droplet growth rate of 1ML/s. Arsenic flux (7-8×10-6Torr) is then exposed for InGaAs crystallization at 200°C for 5 min. During droplet epitaxy at a high droplet thickness and high temperature, out-diffusion from the centre of droplets occurs under anisotropic strain. This leads to quantum ring structures having non-uniform ring stripes and deep square-shaped nanoholes. Using these peculiar quantum rings as templates, four quantum dots situated at the corners of a square shape are regrown. Two of these four quantum dots are aligned either [110] or [110], which are preferable crystallographic directions of quantum dot alignment in general.},
note = {cited By 0},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Laterally close-packed quantum dots (QDs) called quantum dot molecules (QDMs) are grown using a modified molecular beam epitaxy (MBE) method. Quantum dots may be aligned and cross hatched. Quantum rings (QRs) created from quantum dot transformation during thin or partial capping are used as templates for the formations of bi-quantum dot molecules (Bi-QDMs) and quantum dot rings (QDRs). The preferable quantum dot nanostructure for quantum computation based on quantum dot cellular automata (QCA) is laterally close-packed quantum dot molecules having four quantum dots at the corners of square configuration. These four quantum dot sets are called quadra-quantum dots (QQDs). Aligned quadra-quantum dots with two electron confinements work like a wire for digital information transmission using the Coulomb repulsion force, which is fast and consumes little power. A combination of quadra-quantum dots in line and cross-over works as logic gates and memory bits. A molecular Beam Epitaxial growth technique called "Droplet Epitaxy" has been developed for several quantum nanostructures such as quantum rings and quantum dot rings. Quantum rings are prepared by using 20 ML In-Ga (15:85) droplets deposited on a GaAs substrate at 390°C with a droplet growth rate of 1ML/s. Arsenic flux (7-8×10-6Torr) is then exposed for InGaAs crystallization at 200°C for 5 min. During droplet epitaxy at a high droplet thickness and high temperature, out-diffusion from the centre of droplets occurs under anisotropic strain. This leads to quantum ring structures having non-uniform ring stripes and deep square-shaped nanoholes. Using these peculiar quantum rings as templates, four quantum dots situated at the corners of a square shape are regrown. Two of these four quantum dots are aligned either [110] or [110], which are preferable crystallographic directions of quantum dot alignment in general.
49.
Suraprapapich, S; Shen, Y M; Fainman, Y; Horikoshi, Y; Panyakeow, S; Tu, C W
The effects of rapid thermal annealing on doubled quantum dots grown by molecular beam epitaxy Journal Article
In: Journal of Crystal Growth, vol. 311, no. 7, pp. 1791-1794, 2009, ISSN: 00220248, (cited By 6).
@article{Suraprapapich2009,
title = {The effects of rapid thermal annealing on doubled quantum dots grown by molecular beam epitaxy},
author = {S Suraprapapich and Y M Shen and Y Fainman and Y Horikoshi and S Panyakeow and C W Tu},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-63549119433&doi=10.1016%2fj.jcrysgro.2008.12.037&partnerID=40&md5=f1af8add2df18fed2be467c63e2a9300},
doi = {10.1016/j.jcrysgro.2008.12.037},
issn = {00220248},
year = {2009},
date = {2009-01-01},
journal = {Journal of Crystal Growth},
volume = {311},
number = {7},
pages = {1791-1794},
abstract = {The effects of different rapid thermal annealing temperatures on the optical properties of InAs double quantum dots (DQDs) grown by molecular beam epitaxy using a partial-capping-and-regrowth process have been investigated. Improvement of the material quality is indicated by enhanced photoluminescence (PL) intensity and narrower PL linewidth. The blueshift of the PL emission peak with increasing annealing temperature is due to the interdiffusion of group III atoms during the annealing process, which is confirmed by the temperature dependence of the PL peak position. Thermal quenching of the PL intensity is observed at temperature over 110 K, and the main activation energy decreases with annealing temperature, consistent with a reduced confining potential from the interdiffusion of group III atoms. All of these results are similar to those of single quantum dots reported in the literature. © 2008 Elsevier B.V.},
note = {cited By 6},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The effects of different rapid thermal annealing temperatures on the optical properties of InAs double quantum dots (DQDs) grown by molecular beam epitaxy using a partial-capping-and-regrowth process have been investigated. Improvement of the material quality is indicated by enhanced photoluminescence (PL) intensity and narrower PL linewidth. The blueshift of the PL emission peak with increasing annealing temperature is due to the interdiffusion of group III atoms during the annealing process, which is confirmed by the temperature dependence of the PL peak position. Thermal quenching of the PL intensity is observed at temperature over 110 K, and the main activation energy decreases with annealing temperature, consistent with a reduced confining potential from the interdiffusion of group III atoms. All of these results are similar to those of single quantum dots reported in the literature. © 2008 Elsevier B.V.
50.
Boonpeng, P; Panyakeow, S; Ratanathammaphan, S
Fabrication of In0.15Ga0.85As nanohloes on GaAs by droplet molecular beam epitaxy Journal Article
In: Journal of Crystal Growth, vol. 311, no. 7, pp. 1843-1846, 2009, ISSN: 00220248, (cited By 1).
@article{Boonpeng2009a,
title = {Fabrication of In0.15Ga0.85As nanohloes on GaAs by droplet molecular beam epitaxy},
author = {P Boonpeng and S Panyakeow and S Ratanathammaphan},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-63349093032&doi=10.1016%2fj.jcrysgro.2008.10.066&partnerID=40&md5=206984df31031eb7c20c92a964642f0c},
doi = {10.1016/j.jcrysgro.2008.10.066},
issn = {00220248},
year = {2009},
date = {2009-01-01},
journal = {Journal of Crystal Growth},
volume = {311},
number = {7},
pages = {1843-1846},
abstract = {This article reports on the fabrication of self-assembled In0.15Ga0.85As nanoholes on GaAs(1 0 0)substrates grown by droplet epitaxy using molecular beam epitaxy. The effects of growth interruption time and substrate temperature were investigated. The surface morphology of In0.15Ga0.85As nanoholes were examined by atomic force microscopy. The results show the dependence of density, depth, and width of nanoholes on the growth interruption time and substrate temperature. This growth technique is simple and flexible. It does not require additional complicated substrate processing and has a potential in developing quantum dots and quantum dot molecules for quantum computation applications. © 2008 Elsevier B.V. All rights reserved.},
note = {cited By 1},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This article reports on the fabrication of self-assembled In0.15Ga0.85As nanoholes on GaAs(1 0 0)substrates grown by droplet epitaxy using molecular beam epitaxy. The effects of growth interruption time and substrate temperature were investigated. The surface morphology of In0.15Ga0.85As nanoholes were examined by atomic force microscopy. The results show the dependence of density, depth, and width of nanoholes on the growth interruption time and substrate temperature. This growth technique is simple and flexible. It does not require additional complicated substrate processing and has a potential in developing quantum dots and quantum dot molecules for quantum computation applications. © 2008 Elsevier B.V. All rights reserved.