Electron transport and photoelectric properties in glow discharge a-Si:H films prepared from disilane

The electron transport and photoelectric properties in a-Si:H films prepared from disilane by an rf glow-discharge decomposition process have been measured as a function of substrate temperature and have been compared with those prepared from monosilane. At substrate temperatures below 200°C, the electron transport properties of disilane films are inferior to those monosilane films because of the preferential formation of highly disordered polysilane structures in disilane films. Substrate temperatures higher than 200°C yield disilane and monosilane films nearly the same electron mobility and photoconductivity at room temperature. The temperature dependence of the electron mobility reveals a significant difference in the tail state distribution below the conduction band between disilane and monosilane films. This suggests that local atomic structures of a-Si: H films depend critically on source gas species, even if the room-temperature properties are apparently the same.