Conduction properties of highly conductive a-Si:H:Y alloy films at low temperature

Conductive n-type a-Si:H:Y alloy films with the conductivity as high as 60 S/cm have been deposited on Si substrate by radio frequency sputtering. In the temperature range 20 similar to 300 K, for samples with large Y contents, the thermally activated conduction is also observed and the plots of lg sigma vs. 1/T can be fitted by two linear functions with different slopes. The corresponding temperatures of the kinks between the two straight lines depend on the Y contents in the samples. For small Y content films, the conductivities can be fitted to the funciton sigma proportional to exp (-1/T-1/4). The present results are interpreted using different conduction mechanisms in different temperature ranges for samples with different Y contents.