Charge-carrier transport and recombination in heteroepitaxial CdTe

Journal Article · Sun Sep 28 00:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4896673· OSTI ID:22305690

Kuciauskas, Darius; Farrell, Stuart; Dippo, Pat; Moseley, John; Moutinho, Helio; Li, Jian V.; Allende Motz, A. M.; Kanevce, Ana; Zaunbrecher, Katherine; Gessert, Timothy A.; Levi, Dean H.; Metzger, Wyatt K. ^[1]; Colegrove, Eric; Sivananthan, S. ^[2]

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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)

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 S_surface = (2.8 ± 0.3) × 10⁵cm s ⁻¹) and at the heteroepitaxial interface (interface recombination velocity S_interface = (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.

• OSTI ID: 22305690
• Journal Information: Journal of Applied Physics, Vol. 116, Issue 12; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Publisher: American Institute of Physics (AIP)
• Country of Publication: United States
• Language: English

Related Subjects

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