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Proceedings Paper

A detailed investigation on the impact of variation in monolayer coverage on optical properties of InAs/GaAs multilayer quantum dot heterostructure
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Paper Abstract

The influence of variation in InAs monolayer coverage on the formation of self-assembled quantum dots (QDs) grown by molecular beam epitaxy (MBE) was investigated by Photoluminescence (PL), Photoluminescence excitation (PLE), and High-resolution X-ray diffraction (HRXRD) measurements. Redshift in the PL spectra was observed with increase in monolayer (ML) coverage of InAs QD from 2 ML to 3.4 ML, as a consequence of an increase in dot size. However, the PL peak intensity initially enhanced from 2 ML to 2.7 ML followed by a drop in 3.4 ML, which promulgate the incoherent dot formation along with the facilitation of defects. The full width at half maxima (FWHM) of the lowtemperature ground state emission spectra was found to be around 48 meV for 2 ML and 3.4 ML InAs QD, but for 2.7 ML it was around 40 meV as a result of lower dispersion in dot size. PLE spectra and a prolonged double-peak feature in the power dependent PL spectra revealed that the transition of the size distribution of InAs QD from single-modal to bimodal occurred as the InAs QD coverage increased. Besides, HRXRD measurements explained the formation of compressively strained QDs with increased InAs coverage. The activation energy for all samples was calculated from the temperature-dependent photoluminescence spectra and the optimum value (~327 meV) obtained for 2.7 ML sample, which attributes deeper barrier potential. Thus, possessing efficient activation energy, relaxed strain and predominantly enhanced luminescence, InAs QD with 2.7 ML coverage is the optimized structure for various optoelectronic device applications.

Paper Details

Date Published: 9 September 2019
PDF: 11 pages
Proc. SPIE 11085, Low-Dimensional Materials and Devices 2019, 110851A (9 September 2019); doi: 10.1117/12.2529014
Show Author Affiliations
Aditya Patel, Indian Institute of Technology Bombay (India)
Debiprasad Panda, Indian Institute of Technology Bombay (India)
Suryansh Dongre, Indian Institute of Technology Bombay (India)
Sanowar Alam Gazi, Indian Institute of Technology Bombay (India)
Debabrata Das, Indian Institute of Technology Bombay (India)
Subhananda Chakrabarti, Indian Institute of Technology Bombay (India)

Published in SPIE Proceedings Vol. 11085:
Low-Dimensional Materials and Devices 2019
Nobuhiko P. Kobayashi; A. Alec Talin; Albert V. Davydov, Editor(s)

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