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Hole Drift-Mobility Measurements and Multiple-Trapping in Microcrystalline Silicon

Published online by Cambridge University Press:  21 March 2011

T. Dylla ,
F. Finger  and
E. A. Schiff
T. Dylla
Affiliation:
Department of Physics, Syracuse University, Syracuse, NY 13244-1130 USA Institut für Photovoltaik, Forschungszentrum Jülich, Jülich, D-52425 Germany
F. Finger
Affiliation:
Institut für Photovoltaik, Forschungszentrum Jülich, Jülich, D-52425 Germany
E. A. Schiff
Affiliation:
Department of Physics, Syracuse University, Syracuse, NY 13244-1130 USA
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Abstract

We present photocarrier time-of-flight measurements of the hole drift-mobility in microcrystalline silicon samples with a high crystalline volume fraction; typical room-temperature values are about 1 cm2/Vs. Temperature-dependent measurements are consistent with the model of multiple-trapping in an exponential bandtail. While this model has often been applied to amorphous silicon, its success for predominantly crystalline samples is unexpected. The valence bandtail width is 31 meV, which is about 10-20 meV smaller than values reported a-Si:H, and presumably reflects the greater order in the microcrystalline material. The hole band-mobility is about 1 cm2/Vs – essentially the same magnitude as has been reported for electrons and for holes in amorphous silicon, and suggesting that this magnitude is a basic characteristic of mobility-edges, at least in silicon-based materials. The attempt-frequency is about 109 s-1; this value is substantially smaller than the values 1011 - 1012 s-1 typically reported holes in amorphous silicon, but the physical significance of the parameter remains obscure.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 808: Symposium A – Amorphous and Nanocrystaline Silicon Science and Technology-2004 , 2004 , A8.10
Copyright
Copyright © Materials Research Society 2004

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