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Proceedings Paper

Carrier dynamics in MOVPE-grown bulk dilute nitride materials for multi-junction solar cells
Author(s): Yongkun Sin; Stephen LaLumondiere; Toby Garrod; Tae Wan Kim; Jeremy Kirch; Luke Mawst; William T. Lotshaw; Steven C. Moss
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Paper Abstract

Dilute nitride materials with a 1eV band-gap lattice matched to GaAs substrates are attractive for high-efficiency multi-junction solar cells. Carrier lifetime measurements are crucial in optimizing material growth and p-i-n field-aided carrier-extraction-device design. One research group has reported carrier lifetimes of MBE-grown bulk InGaNAsSb materials, but there has been no report of carrier lifetime measurements from bulk InGaNAsSb grown by MOVPE. In this study, we report the growth of bulk InGaNAsSb by MOVPE and the first carrier lifetime measurement from MOVPE-grown bulk InGaNAsSb materials with Eg= 1.0 - 1.2eV at 300K. We studied carrier dynamics in MOVPE-grown bulk dilute nitride materials nominally lattice matched to GaAs (100) substrates: 1μm thick In0.035GaN0.025As (Eg= 1.0eV at 300K) and ~0.2μm thick In(0.05-0.07)GaN(0.01-0.02)AsSb(0.02-0.06) layers (Eg= 1.2eV at 300K). Both structures are fully strained. The incorporation of N in InGaNAs leads to degradation in photoluminescence efficiency, but prior studies indicate the addition of Sb in MBE-grown InGaNAsSb improved the PL efficiency. Two-step post-growth thermal annealing processes were optimized to obtain maximum PL efficiencies that yielded a typical blue shift of 50 and 30meV for InGaNAs and InGaNAsSb, respectively. We employed a streak camera to measure carrier lifetimes from both as-grown and thermally annealed samples. Carrier lifetimes of <30psec were obtained from the InGaNAs samples, whereas carrier lifetimes of up to ~150psec were obtained from the InGaNAsSb samples. We discuss possible reasons for short carrier lifetimes measured from MOVPE-grown InGaNAs(Sb) materials.

Paper Details

Date Published: 21 February 2011
PDF: 11 pages
Proc. SPIE 7933, Physics and Simulation of Optoelectronic Devices XIX, 79330H (21 February 2011); doi: 10.1117/12.873894
Show Author Affiliations
Yongkun Sin, The Aerospace Corp. (United States)
Stephen LaLumondiere, The Aerospace Corp. (United States)
Toby Garrod, Univ. of Wisconsin-Madison (United States)
Tae Wan Kim, Univ. of Wisconsin-Madison (United States)
Jeremy Kirch, Univ. of Wisconsin-Madison (United States)
Luke Mawst, Univ. of Wisconsin-Madison (United States)
William T. Lotshaw, The Aerospace Corp. (United States)
Steven C. Moss, The Aerospace Corp. (United States)

Published in SPIE Proceedings Vol. 7933:
Physics and Simulation of Optoelectronic Devices XIX
Bernd Witzigmann; Fritz Henneberger; Yasuhiko Arakawa; Alexandre Freundlich, Editor(s)

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