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Proceedings Paper

Ultrafast density-and-temperature-dependent carrier dynamics in a quantum dots-in-a-well heterostructure
Author(s): R. P. Prasankumar; R. V. Shenoi; J. Urayama; W. W. Chow; S. Krishna; A. J. Taylor
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Paper Abstract

The incorporation of semiconductor quantum dots into different heterostructures for applications in nanoscale photodetection, lasing and amplification has been an active area of research in recent years. Here, we use ultrafast differential transmission spectroscopy to temporally and spectrally resolve density-and-temperature-dependent carrier dynamics in an InAs/InGaAs quantum dots-in-a-well (DWELL) heterostructure. In our experiments, electron-hole pairs are optically injected into the three dimensional GaAs barriers, after which we monitor carrier relaxation into the two dimensional InGaAs quantum wells and the zero dimensional InAs quantum dots by tuning the probe photon energy. We find that for low photoinjected carrier densities, carrier capture and relaxation are dominated by Auger carrier-carrier scattering at low temperatures, with thermal emission playing an increasing role with temperature. At low temperatures we also observe excitation-dependent shifts of the quantum dot energy levels. In contrast, high density measurements reveal an anomalous induced absorption at the quantum dot excited state that is correlated with quantum well population dynamics. Our experiments provide essential insight into carrier relaxation across multiple spatial dimensions and reveal unique Coulomb interaction-induced phenomena, with important implications for DWELL-based lasers and amplifiers.

Paper Details

Date Published: 21 February 2011
PDF: 12 pages
Proc. SPIE 7937, Ultrafast Phenomena in Semiconductors and Nanostructure Materials XV, 793707 (21 February 2011); doi: 10.1117/12.872887
Show Author Affiliations
R. P. Prasankumar, Los Alamos National Lab. (United States)
R. V. Shenoi, The Univ. of New Mexico (United States)
J. Urayama, Sandia National Labs. (United States)
W. W. Chow, Sandia National Labs. (United States)
S. Krishna, The Univ. of New Mexico (United States)
A. J. Taylor, Los Alamos National Lab. (United States)


Published in SPIE Proceedings Vol. 7937:
Ultrafast Phenomena in Semiconductors and Nanostructure Materials XV
Kong-Thon Tsen; Jin-Joo Song; Markus Betz; Abdulhakem Y. Elezzabi, Editor(s)

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