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

Research output: Contribution to journalArticlepeer-review

89 Scopus citations


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
Issue number5
StatePublished - 1990
Externally publishedYes

ASJC Scopus subject areas

  • Condensed Matter Physics


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