Photo-Induced ESR in Amorphous Si1-xNx:H Films

A large increase in the spin density for ESR signals originating from Si dangling bonds is observed by illumination at liquid nitrogen temperature for a-Si1-xNx:H films prepared by magnetron-sputtering and glow-discharge-decomposition. The photo-induced ESR can be explained as arising from the following three types of centers; (1) negative U centers which have unpaired spins metastable only under illumination, (2) positive U centers which are converted from negative U centers by illumination and (3) dangling bonds created by a bond-breaking by the intense illumination.