Abstract
We have studied gap state profiles and light-induced fatigue in amorphous selenium (a-Se) by means of xerographic discharge measurements. Prolonged illumination increases the density of charged defects in a-Se. Nature of charged defects created by light exposure is similar to that of native structural defects D+ and D- . The formation of charged defects is enhanced by light illumination of photon energy equal to the band gap of a-Se. In addition, the creation efficiency of photo-induced charged defects under an applied electric field is small compared with that under zero field. These experimental results imply that the geminate recombination of electron-hole pairs plays an important role in the creation process of charged defects, D+ and D- in a-Se.
