Photoluminescence related to optically-induced metastable centers in a-As2S3

Abstract A new photoluminescence (PL) band, which grows with above-band-gap irradiation was observed in a-As 2 S 3 . This photoluminescence (PL2) is excited efficiently with below-band-gap energy. The peak energy and full width at half maximum are 0.85eV and 0.38eV, respectively. This peak energy is lower than that of the PL excited with around band-gap energy, which has been studied by many authors (PL1). The PL2 band is not annealed out completely at 220K, while optically induced absorption is annealed out at this temperature. The PL1 fatigued with prolonged irradiation of intense light does not recovers at the temperature. Theses facts suggest that the growth of the PL2 center is rather related to the fatigue of PL1 than the creation of optically induced absorption centers and that there are at least two kinds of optically induced centers in a-As 2 S 3 : one is related to optically induced absorption and the other is related to the fatiguing effect and PL2.