Thin films of hydrogenated amorphous silicon and polycrystalline silicon; oxygen and hydrogen interaction effects on electrical properties

Abstract

The reversible interaction between molecular oxygen and hydrogenated amorphous silicon or polycrystalline silicon surfaces is studied. Coplanar configuration and Schottky structure are used to check the interaction effects. The interaction is reversible and may be explained by electric charge exchange between trapped gas species and semiconductors. The trapped gas species at the semiconductors surface may be considered as electronic centers at the surface. This assimilation explains the trapped and released process of gas species. We use a developed model to extract the desorption characteristics. The hydrogenated amorphous silicon in the metal/semiconductor structure interacts with oxygen and hydrogen. The interaction effects are observed on the courant–voltage ( I– V) characteristics which are fitted by using Schottky model. The characteristic parameters show a significant change. This phenomenon is reversible and may be explained by assuming an electric charge exchange between metal/semiconductor interface and the gas. The interface states formed by the exposure to the gas seem to play a similar role that those formed on the surface of the respective semiconductor films.