DXCenters in Ionic SemiconductorCdF2:Ga

Analysis of thermally and optically induced transformations of metastable Ga centers in the wide-gap, predominantly ionic semiconductor ${\mathrm{CdF}}_2$ points to the existence of two metastable states of the center. The configuration-coordinate model of the center is discussed and its energy parameters are determined. It is concluded that this center is not just “ $\mathrm{DX}$-like,” as was initially assumed, but is a true $\mathrm{DX}$ center with a shallow donor and two deep negative- $U$ states.