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Title: In-situ curvature monitoring and X-ray diffraction study of InGaAsP/InGaP quantum wells

The use of InGaAsP/InGaP quantum well structures is a promising approach for subcells in next generation multi-junction devices due to their tunable bandgap (1.50-1.80 eV) and for being aluminum-free. Despite these potentials, the accumulation of stress during the growth of these structures and high background doping in the quantum well region have previously limited the maximum number of quantum wells and barriers that can be included in the intrinsic region and the sub-bandgap external quantum efficiency to less than 30.0%. In this paper, we report on the use of in-situ curvature monitoring by multi-beam optical stress (MOS) sensor measurements during the growth of this quantum well structure to monitor the stress evolution in these thin films. A series of In 0.32Ga 0.68AsP/In 0.49Ga 0.51P quantum wells with various arsine to phosphine ratios have been analyzed by in-situ curvature monitoring and X-ray diffraction (XRD) to obtain nearly strain-free lattice matched structures. Sharp interfaces, as indicated by the XRD fringes, have been achieved by using triethyl-gallium and trimethyl-gallium as gallium precursors in InGaAsP and InGaP, respectively, with constant flows of trimethyl-indium and phosphine through the entire quantum well structure. The effect of the substrate miscut on quantum well growth was compared andmore » analyzed using XRD, photoluminescence and time resolved photoluminescence. As a result, a 100 period quantum well device was successfully grown with minimal stress and approximately flat in-situ curvature.« less
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [2] ;  [3]
  1. North Carolina State Univ., Raleigh, NC (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. North Carolina State Univ., Raleigh, NC (United States)
Publication Date:
Report Number(s):
NREL/JA-5J00-68858
Journal ID: ISSN 0022-0248
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
Journal of Crystal Growth
Additional Journal Information:
Journal Volume: 475; Journal Issue: C; Journal ID: ISSN 0022-0248
Publisher:
Elsevier
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Solar Energy Technologies Office (EE-4S)
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; metalorganic chemical vapor deposition; quantum wells; semiconducting III-V materials; semiconducting gallium arsenide; semiconducting indium gallium phosphide; solar cells
OSTI Identifier:
1393376