The pressure-induced effects in the thermal equilibrium electron properties of semiconducting glasses

Strong pressure-induced effects in the thermal equilibrium properties of semiconducting glasses are revealed and theoretically analysed. The basic property under consideration is the concentration of the negative-U centres which determine the mobility-gap spectral structure and the related electron phenomena in the materials. For accessible high pressures, , a rapid increase of the concentration with growing pressure is predicted. This holds for (`weak') negative-U centres formed in typical, `rigid', configurations for the vast majority of atoms, as both the mobility-gap width and the related effective magnitude of the negative pair-correlation energy decrease with pressure. However, at ambient (and low) pressure another type of centre, `strong' negative-U centres formed in glassy atomic soft configurations, predominate, whose concentration decreases with increasing pressure. The resulting concentration of negative-U centres and some related characteristics are shown to exhibit a non-monotonic pressure dependence with a minimum. Future experimental tests of the corresponding theoretical relationships might determine the basic parameters of the phenomenon for the materials under consideration.