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Title: Charge-carrier transport and recombination in heteroepitaxial CdTe

We analyze charge-carrier dynamics using time-resolved spectroscopy and varying epitaxial CdTe thickness in undoped heteroepitaxial CdTe/ZnTe/Si. By employing one-photon and nonlinear two-photon excitation, we assess surface, interface, and bulk recombination. Two-photon excitation with a focused laser beam enables characterization of recombination velocity at the buried epilayer/substrate interface, 17.5 μm from the sample surface. Measurements with a focused two-photon excitation beam also indicate a fast diffusion component, from which we estimate an electron mobility of 650 cm² (Vs)⁻¹ and diffusion coefficient D of 17 cm² s⁻¹. We find limiting recombination at the epitaxial film surface (surface recombination velocity Ssurface = (2.8 ± 0.3) × 10⁵cm s ⁻¹) and at the heteroepitaxial interface (interface recombination velocity Sinterface = (4.8 ± 0.5) × 10⁵ cm s⁻¹). The results demonstrate that reducing surface and interface recombination velocity is critical for photovoltaic solar cells and electronic devices that employ epitaxial CdTe.
Authors:
; ; ; ; ; ; ; ; ; ; ;  [1] ; ;  [2]
  1. National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, Colorado 80401-3305 (United States)
  2. Microphysics Laboratory, Physics Department, University of Illinois at Chicago, Chicago, Illinois 60612 (United States)
Publication Date:
OSTI Identifier:
22305690
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 12; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CADMIUM TELLURIDES; CHARGE CARRIERS; DIFFUSION; ELECTRIC CONDUCTIVITY; ELECTRON MOBILITY; EPITAXY; EXCITATION; FILMS; INTERFACES; PHOTOVOLTAIC EFFECT; RECOMBINATION; SILICON; SOLAR CELLS; SPECTROSCOPY; SUBSTRATES; SURFACES; THICKNESS; TIME RESOLUTION; ZINC TELLURIDES