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Effect of tunable dot charging on photoresponse spectra of GaAs p-i-n diode with InAs quantum dots
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2015 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 118, no 24, 244503Article in journal (Refereed) PublishedText
Abstract [en]

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.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2015. Vol. 118, no 24, 244503
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Physical Sciences
URN: urn:nbn:se:kth:diva-181381DOI: 10.1063/1.4937408ISI: 000367535100026ScopusID: 2-s2.0-84953857669OAI: diva2:900268
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Available from: 2016-02-03 Created: 2016-02-01 Last updated: 2016-04-01Bibliographically approved

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Fu, Ying
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