Experimental study of oxygen effect on the variation of resistivity with temperature for polycrystalline selenium thin films

Abstract

A detailed correlation between the temperature dependence of the resistivity of polycrystalline selenium thin films and the presence of oxygen at the grain boundaries is established. The temperature dependence of the dc and ac resistivity and the thermoelectric power of polycrystalline selenium thin film structures are studied as functions of thermal history and ambient gas exposure (argon, air atmosphere, dry oxygen, helium). Annealing at 413 K for 4 h under oxygen results in a decrease of the room temperature resistivity and an increase of the resistivity with increasing temperature from 290 to 350 K. Evidence that these effects are due to oxygen diffusion at the grain boundaries is deduced from ac conductivity dependence of planar structures, thermoelectric dower measurements, and ESCA studies.

Effect of isothermal annealing and visible-light illumination on the AC-impedance behavior of undoped selenium thin films

“…The observed significant increase in Z 0 (x) of undoped Se films (deposited at T S = 50°C and placed in the dark) with increasing T A (P50°C) indicate onset of a semiconductive behavior in these films. This may be attributed to a reduction in the number of native charged defects residing at the dispersed space-charge boundary regions separating the crystallite Se micrograins upon isothermal annealing and thus to a decrease in the height of their interfacial grain-boundary barriers in undoped polycrystalline Se films [25,[31][32][33].…”