The effects of substrate temperature on reactively evaporated a-Si:H

Abstract

The bonding configurations and the concentrations of hydrogen are important parameters that affect the electrical and optical properties as well as the Staebler–Wronsky effect. Infrared transmission measurements are used as the main technique to investigate the effect of substrate temperature Ts on the hydrogen content and bonding configurations in reactively evaporated a-Si:H. There is no measurable SiH peak in films made at low Ts. When Ts is increased to 450 K, the SiH peak is discernable, and the maximum SiH concentration is obtained for Ts = 540 K. SiH2 and(or) (SiH2)n concentrations are large at low Ts but decrease as Ts is increased. When samples made at low Ts are stored in air at room temperature, they take up oxygen and the SiH2 and(or) (SiH2)n concentration decreases with time after preparation. This phenomenon is not observed for samples made with Ts ≥ 540 K. The dark conductivity, optical band gap, and electrical activation energy are altered by varying the H concentration. When some samples [Formula: see text] are illuminated with AM1 radiation, a conductivity change of more than three orders of magnitude has been observed.