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Title: Effect of tunable dot charging on photoresponse spectra of GaAs p-i-n diode with InAs quantum dots

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.
Authors:
; ; ; ; ; ;  [1] ;  [2] ;  [3]
  1. State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China)
  2. 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)
  3. Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, SE-10691 Stockholm (Sweden)
Publication Date:
OSTI Identifier:
22493099
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 118; Journal Issue: 24; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ELECTRON CAPTURE; GALLIUM ARSENIDES; HOLES; INDIUM ARSENIDES; IONIZATION; LAYERS; MODULATION; PHOTODIODES; P-N JUNCTIONS; QUANTUM DOTS; S STATES; SIMULATION; SPECTRA; SPECTROSCOPY; TEMPERATURE DEPENDENCE; TUNNEL EFFECT