The temperature dependence of dark conductivity in hydrogenated amorphous SiN_x films

Thin film samples of hydrogenated amorphous silicon nitride with varying nitrogen content were prepared by conventional plasma deposition from a mixture of SiH₄ and NH₃. The dark conductivity (σ_d) of the films have been measured in the temperature range 420 K - 100 K. The conductivity is thermally activated with a single activation energy down to 250 K and conduction is dominated by electrons in extended states. A strong decrease is observed in σ_d when the nitrogen content is increased.