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- Shang, Xiangjun, et al.
(författare)
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Effect of tunable dot charging on photoresponse spectra of GaAs p-i-n diode with InAs quantum dots
- 2015
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Ingår i: Journal of Applied Physics. - Melville, NY : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 118:24
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Tidskriftsartikel (refereegranskat)abstract
- Quantum dot (QD)-embedded photodiodes have demonstrated great potential for use as detectors. A modulation of QD charging opens intriguing possibilities for adaptive sensing with bias-tunable detector characteristics. Here, we report on a p-i-n GaAs photodiode with InAs QDs whose charging is tunable due to unintentional Be diffusion and trap-assisted tunneling of holes, from bias-and temperature (T)-dependent photocurrent spectroscopy. For the sub-bandgap spectra, the T-dependent relative intensities "QD-s/WL" and "WL/GaAs" (WL: wetting layer) indicate dominant tunneling under -0.9V (trap-assisted tunneling from the top QDs) and dominant thermal escape under -0.2 similar to 0.5V (from the bottom QDs since the top ones are charged and inactive for optical absorption) from the QD s-state, dominant tunneling from WL, and enhanced QD charging at >190K (related to trap level ionization). For the above-bandgap spectra, the degradation of the spectral profile (especially near the GaAs bandedge) as the bias and T tune (especially under -0.2 similar to 0.2V and at >190 K) can be explained well by the enhanced photoelectron capture in QDs with tunable charging. The dominant spectral profile with no degradation under 0.5V is due to a saturated electron capture in charged QDs (i.e., charging neutralization). QD level simulation and schematic bandstructures can help one understand these effects.
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- Song, Yuxin, 1981, et al.
(författare)
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Metamorphic Quantum Well Lasers
- 2012
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Ingår i: Lattice Engineering: Technology and Applications. ; , s. 283-317
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter provides an overview of long wavelengthmetamorphic quantum well lasers. The idea of metamorphic growth is to compromise large lattice mismatch by utilizing a relaxed buffer layer. Structural design and growth optimization of metamorphic buffer layers are reviewed with emphasis on composition grading scheme and doping effects. Progress on long wavelength (>1.2 μm) metamorphic quantum well lasers is summarized.
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- Tångring, Ivar, 1978, et al.
(författare)
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Molecular beam epitaxy growth of A 1.58 μm InGaAs quantum well laser on GaAs
- 2008
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Ingår i: Conference Proceedings - International Conference on Indium Phosphide and Related Materials. - 1092-8669. - 9781424422593
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Konferensbidrag (refereegranskat)abstract
- We demonstrate how MBE growth parameters can be optimized to produce a metamorphic InGaAs QW laser emitting in the 1.55 ?m range. Different techniques to suppress roughening while maintaining low threading dislocation densities are evaluated. Finally, we demonstrate a 50×1250 ?m 2 broad area FabryPerot laser that produces pulsed lasing with a threshold current density of 490 A/cm2 and a wavelength of 1.58 ?m at room temperature.
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- Wang, Lijuan, et al.
(författare)
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Enhanced tunneling in the GaAs p(+)-n(+) junction by embedding InAs quantum dots
- 2012
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Ingår i: Semiconductor Science and Technology. - : IOP Publishing. - 0268-1242 .- 1361-6641. ; 27:11, s. 115010-
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Tidskriftsartikel (refereegranskat)abstract
- GaAs p(+)-n(+) junctions with and without a layer of InAs quantum dots (QDs) embedded at the interface are discussed in this article. The current density versus voltage (I-V) characteristics show that the junctions without QDs are weak degenerate due to the Beryllium(Be) atoms diffusion of nominal p(++)-GaAs; the junctions with QDs generate enhanced tunneling current at forward bias, because the QDs layer reduces the Be diffusion and enables a two-step tunneling process. At room temperature, the current density of the sample with QDs is enhanced to 122 A cm(-2) at a forward bias of +0.32 V, which is about 2 orders of magnitude higher than the reference sample without QDs.
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