Dependence on substrate temperature of the film structure of μc-Si:H prepared by RF magnetron sputtering

Abstract

We prepared hydrogenated microcrystalline silicon (μc-Si:H) films by the RF magnetron sputtering method using an argon/hydrogen gas mixture, and investigated the dependence of the film structure on substrate temperature during deposition. The deposition rate was almost constant when the substrate temperature was between 70°C and 150°C, and also between 200°C and 350°C. However, it decreased by 25% when the substrate temperature was increasing from 150°C to 200°C. The hydrogen concentration in the films showed the same dependence of the deposition rate. These findings suggest that the surface reaction changed with increasing substrate temperature. X-ray diffraction (XRD) spectra revealed that the films prepared below 100°C were amorphous, while the films prepared above 120°C were microcrystalline in nature. The XRD peak intensity and the mean crystalline size, as estimated from the XRD peak width increased with increasing substrate temperature. This suggests that, control of the substrate temperature is very important in order to prepare μc-Si:H films with a high degree of crystallinity.