Charge-carrier transport and recombination in heteroepitaxial CdTe

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

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Abstract

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) × 105cm 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.

Original languageEnglish
Article number123108
JournalJournal of Applied Physics
Volume116
Issue number12
DOIs
Publication statusPublished - 2014 Jan 1

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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    Kuciauskas, D., Farrell, S., Dippo, P., Moseley, J., Moutinho, H., Li, J. V., Allende Motz, A. M., Kanevce, A., Zaunbrecher, K., Gessert, T. A., Levi, D. H., Metzger, W. K., Colegrove, E., & Sivananthan, S. (2014). Charge-carrier transport and recombination in heteroepitaxial CdTe. Journal of Applied Physics, 116(12), [123108]. https://doi.org/10.1063/1.4896673