Fast growth of hydrogenated amorphous silicon from dichlorosilane

Abstract

We report the discovery of very high growth rates of hydrogenated amorphous silicon (a-Si:H) from a glow discharge in dichlorosilane (SiH2Cl2) with small additions of silane (SiH4). The growth rate reaches ∼50 Å s−1 at substrate temperatures between 200 and 300 °C. The rate depends on substrate temperature and is correlated with the concentrations of hydrogen and chlorine in the films in a way that suggests a SiH4-catalyzed mutual elimination of Cl and H from the growing surface. We observe no dust, and no growth on the cold walls of the chamber. The film properties suggest material close to device quality, with dark conductivities of ∼10−12 S cm−1 and photoconductivities of ∼10−7 S cm−1. We measured a midgap defect density of 3.3×1016 cm−3 in an as-grown film, and 4.5×1016 cm−3 after 73 h of light soaking at 1 W cm−2.