ELECTRICAL-PROPERTIES OF HEAVILY-DOPED MU-C-SI-H

We have investigated the conduction in heavily doped mu c-Si:H samples grown by glow discharge by measuring the conductivity and the Hall co efficient in a wide temperature range. We show that the conductivity o f these materials cannot be satisfactorily interpreted using the model s already present in the literature. We put forward a model in which t he material is considered composed of small crystalline grains embedde d in an amorphous tissue and in which potential barriers exist between adjacent grains due to the band discontinuities. A comparison between detailed calculations and transport data shows that the tunneling (pr obably aided by the presence of localized states) is the fundamental c onduction mechanism. (C) 1995 American Institute of Physics.