Anneal-induced degradation of amorphous selenium characterized by photoconductivity measurements

Photoconductivity measurements of amorphous selenium (a-Se) and arsenic selenide (a-AS(2)Se(3)) were carried out. Samples where annealed from 333-358 K at 5 K step for 5 minutes and the photoconductivity was measured after each annealing step. It was found that the dark current increases permanently for a-Se and the photoconductivity ratio increased drastically after 338 K, but drops after further annealing. Amorphous-As2Se3 however, has no noticeable change in the dark current neither in the photoconductivity ratio. Arsenic is introduced into a-Se to prevent degradation, which causes loss of image quality, but the volume must be controlled in order to maintain high photoconductivity.