On the anomalous steady-state dark conductivity in a-se films

Thin films of amorphous selenium (a-Se) have been prepared by thermal evaporation. DC conductivity measurements were carried out on these films in the temperature range between 60 and -50°C. Above room temperature, the dark conductivity is thermally activated as usually observed in chalcogenide semiconductors. At low temperatures, the unexpected increase in the dark currents could be attributed to the phase change in the a-Se film. The currentvoltage, IV, curves showed a phase transition temperature of about 10°C.