A novel preparation technique for preparing hydrogenated amorphous silicon with a more rigid and stable Si network

Abstract

A novel preparation technique, termed ‘‘chemical annealing,’’ was developed with the aim of making a stable and rigid Si network structure. The hydrogen content (C_H) in the films and the optical gap could be reduced gradually without any change in substrate temperature by alternating deposition of a hydrogenated amorphous silicon layer several tens of Å thick and treatment with atomic hydrogen. These films showed C_H of 1.5–10 at. %, and exhibited high photoconductivities in the level of 10⁻⁵–10⁻⁴ S/cm. In the films with C_H of 3 at. % or less, in particular, improvement was observed in stability against illumination with light. Their photoconductivity remained at about 65% of the initial value even after illumination with white light (AM1, 100 mW) for 60 h. In addition, time‐of‐flight experiments revealed a significant enhancement in hole drift mobility to a value of 0.2 cm²/V s at 300 K.