Fast Deposition of Highly Crystallized Microcrystalline Si Films Utilizing a High-Density Microwave Plasma Source for Si Thin Film Solar Cells

Abstract

AbstractIn this work, we investigate the influences of source gas supply method and dc substrate bias on the deposition rate as well as structural properties of μc-Si films and demonstrate the high rate synthesis of highly crystallized μc-Si films with improved film density by using a high-density and low-temperature microwave plasma source. A high flux of SiH3 and atomic hydrogen on film growing surface achieved through adjusting SiH4 gas supply configuration is effective for the fast deposition of highly crystallized μc-Si films and for the improvement of film mass density. Appropriate ion bombardment under moderate negative dc substrate bias along with the suppression of contributions of detrimental species to film growth also account for the improvement in properties of resulting films. As a consequence, a very fast deposition rate of ~65 Å/s was achieved with a high Raman crystallinity Ic/Ia>3 and a low defect density of (1-2)×1016 cm-3 despite a high silane concentration of 67%.