Ab initio estimate of temperature dependence of electrical conductivity in a model amorphous material:: Hydrogenated amorphous silicon

We present an ab initio calculation of the dc conductivity of amorphous silicon and hydrogenated amorphous silicon. The Kubo-Greenwood formula is used to obtain the dc conductivity, by thermal averaging over extended dynamical simulation. Its application to disordered solids is discussed. The conductivity is computed for a wide range of temperatures and doping is explored in a naive way by shifting the Fermi level. We observed the Meyer-Neldel rule for the electrical conductivity with E-MNR=0.06 eV and a temperature coefficient of resistance close to experiment for a-Si:H. In general, experimental trends are reproduced by these calculations, and this suggests the possible utility of the approach for modeling carrier transport in other disordered systems.