Use of a GaAsSb buffer layer for the formation of small, uniform, and dense InAs quantum dots

Ban, Keun-Yong; Bremner, Stephen; Liu, Guangming; Dahal, Som; Dippo, P.; Norman, A. G.; Honsberg, Christiana B.

doi:10.1063/1.3409691

Cited by 42 publications

(16 citation statements)

References 20 publications

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“…When the CL covers a QD, nitrogen fosters the Sb to accumulate on top of the partially relaxed InAs QDs since GaSb has a very similar lattice constant with InAs. On the other hand, as the composition threshold for the total restraint of GaAsSb/InAs QD dissolution in the capping process is around 11% to 14% of Sb [26,27], we could assume that the dissolution process of InAs QDs during the capping growth is completely suppressed for both samples and that the In atoms are not being relocated from the top of the QDs to the QD base [1,7,28]. This explains why no significant differences in the size and morphology of the QDs are seen in both samples.…”

Section: Resultsmentioning

confidence: 99%

Impact of N on the atomic-scale Sb distribution in quaternary GaAsSbN-capped InAs quantum dots

et al. 2012

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The use of GaAsSbN capping layers on InAs/GaAs quantum dots (QDs) has recently been proposed for micro- and optoelectronic applications for their ability to independently tailor electron and hole confinement potentials. However, there is a lack of knowledge about the structural and compositional changes associated with the process of simultaneous Sb and N incorporation. In the present work, we have characterized using transmission electron microscopy techniques the effects of adding N in the GaAsSb/InAs/GaAs QD system. Firstly, strain maps of the regions away from the InAs QDs had revealed a huge reduction of the strain fields with the N incorporation but a higher inhomogeneity, which points to a composition modulation enhancement with the presence of Sb-rich and Sb-poor regions in the range of a few nanometers. On the other hand, the average strain in the QDs and surroundings is also similar in both cases. It could be explained by the accumulation of Sb above the QDs, compensating the tensile strain induced by the N incorporation together with an In-Ga intermixing inhibition. Indeed, compositional maps of column resolution from aberration-corrected Z-contrast images confirmed that the addition of N enhances the preferential deposition of Sb above the InAs QD, giving rise to an undulation of the growth front. As an outcome, the strong redshift in the photoluminescence spectrum of the GaAsSbN sample cannot be attributed only to the N-related reduction of the conduction band offset but also to an enhancement of the effect of Sb on the QD band structure.

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Section: Resultsmentioning

confidence: 99%

Impact of N on the atomic-scale Sb distribution in quaternary GaAsSbN-capped InAs quantum dots

et al. 2012

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“…X-ray and TEM data shown that density of dislocation loops increased from 2 -3 10 2 cm -1 , almost the same for both {110} directions at 8% Sb structure to significantly anisotropic in 16% Sb structure, from 1 10 4 cm -1 for [110] direction up to 4 10 4 cm -1 for [1][2][3][4][5][6][7][8][9][10] direction. RSM (224) reflection picture measured for [1][2][3][4][5][6][7][8][9][10] azimuth direction revealed small anisotropic relaxation of initial elastic stress ( 6.5 ± 1.5%) in this structure. X-ray investigations of 37% Sb composition structure demonstrated significant increase of structural deterioration: total density of 60 secondary dislocation loops in the volume of this structure increased up to 1.25 10 10 cm -2 while vertical and lateral coherence lengths diminished by few times.…”

Section: X-ray and Tem Datamentioning

confidence: 86%

“…To effectively realize these devices, particularly the IBSCs, control of the QD structural and optoelectronic properties is required. The tunability of self-assembled QDs depends on the impact of growth parameters such as substrate temperature, deposition rate and stoichiometry on atom's deposition [5,6]. For most QDs devices high density of QDs with near identical morphology is desired.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the main correlations between structural and physical propertiess of InAs quantum dots, embedded between strain-relief GaAsSb layers

Faleev

Ban

Bremner

et al. 2011

2011 37th IEEE Photovoltaic Specialists Conference

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Strong correlations between crystal perfection of epitaxial structures and size, density and PL features of deposited InAs QDs have been found. Increase of a Sb composition in GaAsSb strain relief layers from 8% to 37% significantly disturbed crystal perfection of epitaxial structures and increased the density of deposited QDs from 2 -2.5 10 10 cm -2 at 8% Sb structure to 7.5 -9.5 10 10 cm -2 at 16% Sb structure. At 37% Sb initial elastic stress was noticeably relaxed ( 40%) while creation of QDs was fully blocked. Relaxation of elastic stress strongly increased the density of dislocation loops in epitaxial layers and affected atomic migration on the growth front. Observed correlations between density of dislocation loops and QDs are related with a diminution of the energy of migrated atoms, caused by dislocations. At definite density of dislocation loops, reduced energy diminished accumulation of deposited atoms below the level critical for their transformation to QDs.

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“…[1,2] In order to realize IBSCs with the InAs QDs, it is required to simultaneously achieve high density and uniformity of QDs for the high light absorption. [3] According to our previous work InAs/GaAsSb is one of the most promising material systems since it has small valence band offset (VBO) and gives good QD properties such as small size, high density and uniformity by Sb content. [3,4] At this point, it is crucial to investigate optical properties of InAs/GaAsSb to address its band structure.…”

Section: Introductionmentioning

confidence: 99%

Detection of the third transition of InAs/GaAsSb quantum dots

Ban

Bremner

Kuciauskas

et al. 2011

2011 37th IEEE Photovoltaic Specialists Conference

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We have investigated InAs quantum dots (QDs) on GaAsSb barrier layers. Low temperature photoluminescence (PL) for InAs/GaAsSb with various δdoping levels is performed to observe interband transitions. PL spectra of heavily doped QD samples show that the electrons injected from the δ-doping plane increase the intensity of the emission peak between the electron and hole first excited states, E1H1, not observed from undoped and lightly QD samples. Time resolved photoluminescence (TRPL) data as a function of δ-doping density reveal that the introduction of a δ-doping plane in the GaAsSb barrier decreases a carrier lifetime making recombination between ground states in QD area faster.As an evidence of carriers more injected from a δ-doping plane an Arrhenius fitting curve taken from temperature dependent PL indicates that the doped samples have the greater thermal activation energies than those of the lightly doped samples. Additionally, intersubband transitions of 20 multiple InAs QDs embedded in GaAsSb barriers are experimentally determined by low temperature (77K) Fourier Transformation-Infrared Spectroscopy (FT-IR) using a multiple internal reflection technique. It is noted that there is a broad peak around about 240meV corresponding to the energy separation between the electron ground state and the continuum state in the conduction band offset (CBO). The band structure based upon an eight band k.p method confirms the experimental results observed here. Furthermore, all related physical phenomena will be discussed as well 978-1-4244-9965-6/11/$26.00 ©2011 IEEE

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Use of a GaAsSb buffer layer for the formation of small, uniform, and dense InAs quantum dots

Cited by 42 publications

References 20 publications

Impact of N on the atomic-scale Sb distribution in quaternary GaAsSbN-capped InAs quantum dots

Impact of N on the atomic-scale Sb distribution in quaternary GaAsSbN-capped InAs quantum dots

Investigation of the main correlations between structural and physical propertiess of InAs quantum dots, embedded between strain-relief GaAsSb layers

Detection of the third transition of InAs/GaAsSb quantum dots

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