High oxygen and carbon contents in GaAs epilayers grown below a critical substrate temperature by molecular beam epitaxy

Goo, C. H.; Lau, W. S.; Chong, Tow Chong; Tan, Leng Seow; Chu, Paul K.

doi:10.1063/1.116551

Cited by 6 publications

(6 citation statements)

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“…The presence of carbon in the samples was also confirmed by secondary ion mass spectroscopy. Using a ring density of 1 × 10 10 cm –2 and assuming no carbon in the high-growth-temperature (∼ 580 °C) GaAs spacer layers, we can estimate the p-doping concentration in the capping layers (the hot and cold caps) to be approximately 1 × 10 16 and 6 × 10 16 cm –3 in samples A and B, respectively, which are of the same order of magnitude as those reported in ref .…”

Section: Resultssupporting

confidence: 63%

“…The introduction of a “cold cap” procedure, in which the QRs were capped at a lower growth temperature (at 430 °C) to reduce As–Sb exchange, helped to preserve the rings and improved the QR PL intensity. However, this growth temperature is much lower than the optimum for high-quality GaAs (580 °C), which results in poor quality material, which increases the background carrier concentration . In an SC, this could increase the dark current and, in turn, reduce the open-circuit voltage.…”

Section: Introductionmentioning

confidence: 99%

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Long-Wavelength Photoluminescence from Stacked Layers of High-Quality Type-II GaSb/GaAs Quantum Rings

Carrington

Young

Hodgson

et al. 2013

Crystal Growth & Design

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We report the successful molecular-beam epitaxial growth of 10 stacked layers of GaSb/GaAs quantum rings using a new procedure. Exact control of the arsenic flux during capping helps to reduce the strong group-V As−Sb exchange reactions, enabling the rings to be capped at the same growth temperature (480 °C) without dissolution. X-ray diffraction and transmission electron microscopy indicate excellent structural quality and uniformity with no threading dislocations. This is due to the reduction in the average strain through the quantum-ring formation. The total ring density in the stacks is 1 × 10 11 cm −2 . An unusually long-wavelength quantum-ring photoluminescence peak of 1.3 μm is observed at low temperature, which is attributed to a reduction in the quantum-ring charging due to lower unintentional p-doping in the GaAs cap layer. The impact that this effect will have on future device designs in solar cells and lasers is also discussed.

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Section: Resultssupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Long-Wavelength Photoluminescence from Stacked Layers of High-Quality Type-II GaSb/GaAs Quantum Rings

Carrington

Young

Hodgson

et al. 2013

Crystal Growth & Design

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“…It has been shown that higher temperature MBE growth of GaAs decreases the incorporation of unintentional p-dopants. 38 Therefore the lower E 0 value for Sample J may indicate less background doping, with fewer holes in the QRs, a reduced recombination rate, and thus a higher exponent than any of the other samples.…”

Section: Discussionmentioning

confidence: 99%

Blueshifts of the emission energy in type-II quantum dot and quantum ring nanostructures

Hodgson

Young

Kamarudin

et al. 2013

Journal of Applied Physics

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We have studied the ensemble photoluminescence (PL) of 11 GaSb/GaAs quantum dot/ring (QD/QR) samples over !5 orders of magnitude of laser power. All samples exhibit a blueshift of PL energy, DE, with increasing excitation power, as expected for type-II structures. It is often assumed that this blueshift is due to band-bending at the type-II interface. However, for a sample where charge-state sub-peaks are observed within the PL emission, it is unequivocally shown that the blueshift due to capacitive charging is an order of magnitude larger than the band bending contribution. Moreover, the size of the blueshift and its linear dependence on occupancy predicted by a simple capacitive model are faithfully replicated in the data. In contrast, when QD/QR emission intensity, I, is used to infer QD/QR occupancy, n, via the bimolecular recombination approximation (I / n 2 ), exponents, x, in DE / I x are consistently lower than expected, and strongly sample dependent. We conclude that the exponent x cannot be used to differentiate between capacitive charging and band bending as the origin of the blueshift in type-II QD/QRs, because the bimolecular recombination is not applicable to type-II QD/QRs. V C 2013 AIP Publishing LLC.

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“…12,13 Moreover, the low-temperature growth also strongly influences the formation of GaAs, and increases the incorporation of carbon impurities. 14 This, as we shall show, can be exploited. Recombination between confined electrons and acceptor-bound holes has a number of advantages for the study of novel physical phenomena in semiconductor nanostructures.…”

mentioning

confidence: 99%

Phonon bottleneck in GaAs/AlxGa1−xAs quantum dots

et al. 2015

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We report low-temperature photoluminescence measurements on highly-uniform GaAs/AlxGa1−xAs quantum dots grown by droplet epitaxy. Recombination between confined electrons and holes bound to carbon acceptors in the dots allow us to determine the energies of the confined states in the system, as confirmed by effective mass calculations. The presence of acceptor-bound holes in the quantum dots gives rise to a striking observation of the phonon-bottleneck effect.

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High oxygen and carbon contents in GaAs epilayers grown below a critical substrate temperature by molecular beam epitaxy

Cited by 6 publications

References 0 publications

Long-Wavelength Photoluminescence from Stacked Layers of High-Quality Type-II GaSb/GaAs Quantum Rings

Long-Wavelength Photoluminescence from Stacked Layers of High-Quality Type-II GaSb/GaAs Quantum Rings

Blueshifts of the emission energy in type-II quantum dot and quantum ring nanostructures

Phonon bottleneck in GaAs/AlxGa1−xAs quantum dots

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