@article{Khoklang2015a,

title = {Molecular beam epitaxial growth of GaSb quantum dots on (0 0 1) GaAs substrate with InGaAs insertion layer},

author = {K Khoklang and S Kiravittaya and M Kunrugsa and P Prongjit and S Thainoi and S Ratanathammaphan and S Panyakeow},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84979959088&doi=10.1016%2fj.jcrysgro.2015.02.044&partnerID=40&md5=7cf71b7ba20245860fae84a168b8ec2e},

doi = {10.1016/j.jcrysgro.2015.02.044},

issn = {00220248},

year  = {2015},

date = {2015-01-01},

journal = {Journal of Crystal Growth},

volume = {425},

pages = {291-294},

publisher = {Elsevier B.V.},

abstract = {We report on the molecular beam epitaxial growth of self-assembled GaSb quantum dots (QDs) on (0 0 1) GaAs substrates with an insertion layer. The insertion layer, which is a 4-monolayers (MLs) InxGa1-xAs (x=0.00, 0.07, 0.15, 0.20 and 0.25), is grown prior to the QD growth. With this InGaAs insertion layer, the obtained QD density decreases substantially, while the QD height and diameter increase as compared with typical GaSb QDs grown on conventional (0 0 1) GaAs surface under the same growth condition. The GaSb QDs on GaAs have the dome shape with elliptical base and the elongation direction of the base is along the [1 1 0] direction. When the InGaAs insertion layer is introduced, the distinct elongation disappears and the QD sidewall shows facet-related surfaces with (0 0 1) plateau on top. © 2015 Elsevier B.V. All rights reserved.},

note = {cited By 3},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Kunrugsa2015a,

title = {GaSb/GaAs quantum-ring-with-dot structures grown by droplet epitaxy},

author = {M Kunrugsa and S Panyakeow and S Ratanathammaphan},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84922496126&doi=10.1016%2fj.jcrysgro.2015.01.026&partnerID=40&md5=dece11e0887f6cbe7be5fd652ebd29b9},

doi = {10.1016/j.jcrysgro.2015.01.026},

issn = {00220248},

year  = {2015},

date = {2015-01-01},

journal = {Journal of Crystal Growth},

volume = {416},

pages = {73-77},

publisher = {Elsevier},

abstract = {We have studied the growth of GaSb/GaAs nanostructures by droplet epitaxy with the variation of Ga deposition temperature which is one of the key parameters. With the use of low Sb flux, GaSb quantum rings (QRs) were formed as a result of the outward diffusion of Ga atoms from the droplets during crystallization. An increase of the deposition temperature results in the larger QR size and the lower QR density due to the longer diffusion length of Ga atoms, which gives rise to the larger initial droplets. Interestingly, some portion of QR lobe breaks up and transforms into a quantum dot (QD) so as to reduce the mismatch strain. A nanostructure containing both QR and QD is called a quantum-ring-with-dot structure (QRDS). As the deposition temperature increases, the nanostructure height distribution changes from unimodal to bimodal behaviors owing to the significant difference between QR and QD heights, whereas the nanostructure diameter still exhibits a unimodal distribution. The bimodal height distribution strongly affects the optical properties and the dynamic of thermal-excited carriers. © 2015 Elsevier B.V. All rights reserved.},

note = {cited By 2},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@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}

}

@article{Laouthaiwattana2009,

title = {Optimization of stacking high-density quantum dot molecules for photovoltaic effect},

author = {K Laouthaiwattana and O Tangmattajittakul and S Suraprapapich and S Thainoi and P Changmuang and S Kanjanachuchai and S Ratanathamaphan and S Panyakeow},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-67349150757&doi=10.1016%2fj.solmat.2008.09.020&partnerID=40&md5=8c52a05098ea229a5b906fbc109f2ed3},

doi = {10.1016/j.solmat.2008.09.020},

issn = {09270248},

year  = {2009},

date = {2009-01-01},

journal = {Solar Energy Materials and Solar Cells},

volume = {93},

number = {6-7},

pages = {746-749},

abstract = {Using a modified molecular beam epitaxial (MBE) process called thin-capping-and-regrowth technique we grew quantum dot molecule (QDM) structures having high dot volume density (greater than 1012 cm-3) and thus suitable as an active layer for effective photovoltaic energy conversion. Stacking of QDMs is time consuming and may introduce defects; therefore, optimization of stack number of QDMs is important in terms of achieving high-performance and low-cost solar cells. Samples with 1, 3, 5, 7 and 10 stacks of high-density QDMs are grown, fabricated into solar cells and characterized optically and electrically. It is found that the solar cell performance initially improves with the number of stacks, yet deteriorates once the number exceeds 5 stacks. We attribute the deterioration to defects and these put the optimized number of QDM stacks in our structure to 3-5. © 2008 Elsevier B.V. All rights reserved.},

note = {cited By 20},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{Panyakeow2009,

title = {Quantum nanostructures by droplet epitaxy},

author = {S Panyakeow},

url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-79961011288&doi=10.4186%2fej.2009.13.1.51&partnerID=40&md5=58446955e9994a8d176f638d1070febf},

doi = {10.4186/ej.2009.13.1.51},

issn = {01258281},

year  = {2009},

date = {2009-01-01},

journal = {Engineering Journal},

volume = {13},

number = {1},

pages = {51-56},

abstract = {Droplet epitaxy is an alternative growth technique for several quantum nanostructures. Indium droplets are distributed randomly on GaAs substrates at low temperatures (120-350°C). Under background pressure of group V elements, Arsenic and Phosphorous, InAs and InP nanostructures are created. Quantum rings with isotropic shape are obtained at low temperature range. When the growth thickness is increased, quantum rings are transformed to quantum dot rings. At high temperature range, anisotropic strain gives rise to quantum rings with square holes and non-uniform ring stripe. Regrowth of quantum dots on these anisotropic quantum rings, Quadra-Quantum Dots (QQDs) could be realized. Potential applications of these quantum nanostructures are also discussed.},

note = {cited By 5},

keywords = {},

pubstate = {published},

tppubtype = {article}

}