Ultrafast recombination and trapping in amorphous silicon

A. Esser, K. Seibert, H. Kurz, G. N. Parsons, C. Wang, B. N. Davidson, G. Lucovsky, R. J. Nemanich

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Abstract

We have studied the time-resolved reflectivity and transmission changes induced by femtosecond laser pulses in hydrogenated and nonhydrogenated amorphous silicon thin films, a-Si:H and a-Si, respectively. By varying the pump power, and hence the photoexcited free-carrier densities, by several orders of magnitude, a quadratic, nonradiative recombination process has been identified that controls the density of free carriers on a picosecond time scale for excitation levels above 5×1018 cm-3 in a-Si:H and above 5×1019 cm-3 in a-Si. At lower free-carrier densities, the reflectivity transients display the dynamics expected from a trapping mechanism. We suggest that the process that dominates for the higher free-carrier densities may result from Auger recombination but with a dependence on the carrier density that is different from that which has been observed in crystalline semiconductors where k selection prevails.

Original languageEnglish (US)
Pages (from-to)2879-2884
Number of pages6
JournalPhysical Review B
Volume41
Issue number5
DOIs
StatePublished - Jan 1 1990
Externally publishedYes

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ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Esser, A., Seibert, K., Kurz, H., Parsons, G. N., Wang, C., Davidson, B. N., Lucovsky, G., & Nemanich, R. J. (1990). Ultrafast recombination and trapping in amorphous silicon. Physical Review B, 41(5), 2879-2884. https://doi.org/10.1103/PhysRevB.41.2879