FURTHER OPTIMIZATION OF AMORPHOUS HYDROGENATED SILICON FILMS FOR SOLAR CELLS BY THE USE OF rf BIAS-SPUTTERING.

Abstract

Optimization of r. f. sputtered amorphous hydrogenated silicon thin films for solar cell applications is usually achieved by control of the hydrogen partial pressure, substrate temperature and r. f. power. This paper describes an additional technique of r. f. bias sputtering for further improvement in material properties. Preliminary results are included on the effect of substrate bias on the electrical and optical parameters of a-Si-H films and related devices. The substrate bias voltage considerably influences the photoconductivity, the illuminated Schottky diode performance and the d. c. room temperature conductivity but the deposition rate and activation energy are affected to a lesser degree; there is no appreciable change to the optical absorption edge.