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The impact of growth rate and barrier thickness on the thermal stability of photoluminescence for coupled InAs/GaAs quantum dot heterostructures with quaternary(InAlGaAs) capping
Author(s): A. Mandal; U. Verma; S. Chakrabarti
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Paper Abstract

Multilayer quantum dots were grown using SSMBE. Seed layer of InAs QD was grown over 1000Å intrinsic GaAs layer on semi-insulating GaAs (001) substrate and capped with 30Å quaternary In0.21Al0.21Ga0.58As and 90Å intrinsic GaAs layer for samples A and B while for sample C it was 20Å and 80Å. Growth rate was 0.2011 ML/s for samples A and C whereas 0.094 ML/s for sample B. Each sample was annealed at 650°C, 700°C, 750°C and 800°C. Greater growth-rate produced more strain in samples A and C producing more dot families and for sample B these increased with annealing because of the interdiffusion of constituents among the QDs. 750°C annealed samples A and C showed higher integrated PL intensity and activation energy because carriers found lower minimum energy states for relaxation, attributed to higher growth rate. In/Ga interdiffusion caused blue shift in photoluminescence(PL) spectra for samples B and C at higher annealing temperatures whereas due to greater capping layer thickness almost no shift for sample A due to intermixing of In-Al between the quaternary alloy and wetting layer, making it thermally stable. Decrease in FWHM due to enhanced carrier relaxation is counterbalanced by non-resonant multi-phonon assisted tunneling processes, suggesting good uniformity.

Paper Details

Date Published: 23 February 2012
PDF: 10 pages
Proc. SPIE 8271, Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling IX, 82710N (23 February 2012); doi: 10.1117/12.907867
Show Author Affiliations
A. Mandal, Indian Institute of Technology Bombay (India)
U. Verma, Indian Institute of Technology Rajasthan (India)
S. Chakrabarti, Indian Institute of Technology Bombay (India)

Published in SPIE Proceedings Vol. 8271:
Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling IX
Kurt G. Eyink; Frank Szmulowicz; Diana L. Huffaker, Editor(s)

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