Spectral response, carrier lifetime, and photocurrents of SiC photocathodes

摘要

Silicon carbide (SiC) photocathode is one of the candidates for energy conversion from the solar light to hydrogen gas. The conversion efficiencies using SiC photocathodes are still low for practical use. In this study, to find origins of low conversion efficiency, we evaluated carrier lifetimes and depletion layer widths in SiC photocathodes and examined relationship of them with photocurrents. In addition, we observed spectral response of the photocurrents from the photocathodes. From these results, we found that enhancement of the carrier lifetime and the depletion layer width is effective for increase of the conversion efficiency for 4H- and 6H-SiC. 3C-SiC would have defects reducing the effective carrier lifetime, and thus decrease of such defects is essential for increase of the conversion efficiency using 3C-SiC. (C) 2016 The Japan Society of Applied Physics