Richards, Robert D., Bastiman, Faebian, Roberts, John S., Beanland, R., Walker, David and David, John P. R. (2015) MBE grown GaAsBi/GaAs multiple quantum well structures : structural and optical characterization. Journal of Crystal Growth, 425 . pp. 237-240. doi:10.1016/j.jcrysgro.2015.02.053

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Abstract

A series of GaAsBi/GaAs multiple quantum well p-i-n diodes were grown by molecular beam epitaxy. Nomarski images showed evidence of sub-surface damage in each diode, with an increase in the cross-hatching associated with strain relaxation for the diodes containing more than 40 quantum wells. X-ray diffraction ω-2θ scans of the (004) reflections showed that multiple quantum well regions with clearly defined well periodicities were grown. The superlattice peaks of the diodes containing more than 40 wells were much broader than those of the other diodes. The photoluminescence spectra showed a redshift of 56 meV and an attenuation of nearly two orders of magnitude for the 54 and 63 well diodes. Calculations of the quantum confinement and strain induced band gap modifications suggest that the wells in all diodes are thinner than their intended widths and that both loss of quantum confinement and strain probably contributed to the observed redshift and attenuation in the 54 and 63 well diodes. Comparison of this data with that gathered for InGaAs/GaAs multiple quantum wells, suggests that the onset of relaxation occurs at a similar average strain-thickness product for both systems. Given the rapid band gap reduction of GaAsBi with Bi incorporation, this data suggests that GaAsBi is a promising photovoltaic material candidate.

Item Type:	Journal Article
Subjects:	Q Science > QC Physics Q Science > QD Chemistry
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	X-rays -- Diffraction, Molecular beam epitaxy , Quantum wells, Bismuth compounds, Gallium compounds, Semiconductors
Journal or Publication Title:	Journal of Crystal Growth
Publisher:	Elsevier BV, North-Holland
ISSN:	0022-0248
Official Date:	1 September 2015
Dates:	Date Event 1 September 2015 Published 23 February 2015 Available 14 February 2015 Accepted 30 October 2014 Submitted
Date of first compliant deposit:	16 December 2016
Volume:	425
Page Range:	pp. 237-240
DOI:	10.1016/j.jcrysgro.2015.02.053
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Open Access
Funder:	Research Councils UK (RCUK)
Grant number:	EP/G037477/1

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