Optically detected ESR of luminescence centers in a‐As2S3

Optically detected ESR (or optically detected magnetic resonance—ODMR) was observed in a‐As2S3 with the microwave of 25GHz and 9.6GHz. Two kinds of signals were observed, which are attributed to the resonance of the triplet exciton and that of the distant electron‐hole pair respectively. Analyzing the width for 25GHz and 9.6GHz, we found that the pair resonance had the unresolved hyperfine structure with an As‐nucleus. The pair resonance was excited with the energy below 2.6eV. This can be explained in terms of the mobility edge.