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Title: Single junction solar cell employing strain compensated GaAs 0.965 Bi 0.035 /GaAs 0.75 P 0.25 multiple quantum wells grown by metal organic vapor phase epitaxy
NSF-PAR ID:
10061115
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  
Publisher / Repository:
American Institute of Physics
Date Published:
Journal Name:
Applied Physics Letters
Volume:
112
Issue:
25
ISSN:
0003-6951
Page Range / eLocation ID:
251105
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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  1. Abstract This work evaluates the passivation efficacy of thermal atomic layer deposited (ALD) Al 2 O 3 dielectric layer on self-catalyzed GaAs 1- x Sb x nanowires (NWs) grown using molecular beam epitaxy. A detailed assessment of surface chemical composition and optical properties of Al 2 O 3 passivated NWs with and without prior sulfur treatment were studied and compared to as-grown samples using x-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and low-temperature photoluminescence (PL) spectroscopy. The XPS measurements reveal that prior sulfur treatment followed by Al 2 O 3 ALD deposition abates III–V native oxides from the NW surface. However, the degradation in 4K-PL intensity by an order of magnitude observed for NWs with Al 2 O 3 shell layer compared to the as-grown NWs, irrespective of prior sulfur treatment, suggests the formation of defect states at the NW/dielectric interface contributing to non-radiative recombination centers. This is corroborated by the Raman spectral broadening of LO and TO Raman modes, increased background scattering, and redshift observed for Al 2 O 3 deposited NWs relative to the as-grown. Thus, our work seems to indicate the unsuitability of ALD deposited Al 2 O 3 as a passivation layer for GaAsSb NWs. 
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