Self-compensation of metastable centers in semiconducting chalcogenide glasses

Abstract

The temperature dependences of magnetic susceptibility are employed for the first time to study the self-compensation of metastable centers with negative correlation energy in the As2S3 chalcogenide glass. The one-electron states of the metastable centers manifest themselves in the Curie paramagnetism at high temperatures, whereas for T≤77 K, one observes an enhancement of antiferromagnetism as a result of spontaneous dissociation of these states 2D0 → D++D−. The observed self-compensation of the paramagnetic centers is similar to the spin-Peierls instability of magnetic lattices, which is supported by the existence of a double peak in the temperature dependence of inverse magnetic susceptibility. This peak identifies the spontaneous dissociation of two different metastable centers for T≤77 K. A comparative analysis of the data on magnetic susceptibility, optically induced absorption, and ESR shows that the one-electron paramagnetic states of these metastable centers (D0) represent native hole and electronic defects formed by the chalcogen and arsenic dangling bonds, respectively. The self-compensation of the two types of metastable centers is enhanced in successive cooling runs 300 K → 3.5 K → 300 K → 3.5 K ... accompanied by optical pumping at an energy close to the Urbach absorption edge, which is reflected in a decrease in the Curie paramagnetism and an enhancement of the van Vleck paramagnetism of two-electron states with negative correlation energy (D−).