Deposition of intrinsic, phosphorus-doped, and boron-doped hydrogenated amorphous silicon films at 50°C

We report the optical and electronic properties of intrinsic and doped hydrogenated amorphous silicon films deposited at 50°C. Comparison of the film properties in the as-deposited and annealed states (1 h at 200°C) suggests that dense and ordered films can be deposited at 50°C. Moreover, the effects of post-deposition annealing support the hypothesis that at low substrate temperature hydrogenated amorphous silicon grows in a metastable state. Annealing produces a decrease of the metastable defect density in the intrinsic films and the activation of dopants in doped films. Our results suggest that the suppression of plasma and surface polymerization reactions, which usually result in the deterioration of the films deposited at 50°C, is of critical importance in obtaining high-quality films.