Effect of tunable dot charging on photoresponse spectra of GaAs p-i-n diode with InAs quantum dots
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China)
- Center for Applied Mathematics and Physics, Halmstad University, P.O. Box 823, S-301 18 Halmstad, Sweden and Solid State Physics/Nanometer Structure Consortium, Lund University, P.O. Box 118, S-221 00 Lund (Sweden)
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, SE-10691 Stockholm (Sweden)
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 −0.9 V (trap-assisted tunneling from the top QDs) and dominant thermal escape under −0.2 ∼ 0.5 V (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 >190 K (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 ∼ 0.2 V 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 0.5 V 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.
- OSTI ID:
- 22493099
- Journal Information:
- Journal of Applied Physics, Vol. 118, Issue 24; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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