It was found that H, which was unintentionally incorporated into a C-doped layer, led to device degradation by increasing the leakage current under minority carrier injection. The presence of so-called isolated H donors led to rapid degradation, and even C-H complexes (which were believed to be neutral) caused slow degradation. The decomposition of C-H complexes freed H which then caused degradation. The decomposition mechanism was suggested to be a charge-state effect which was related to 2-electron capturing.

H.Fushimi, K.Wada: Materials Science Forum, 1995, 196-201, 957-62