An analysis of thermally and optically induced transformations of metastable Ga centers in this wide-gap mainly ionic semiconductor indicated the existence of 2 metastable states for the center. The configuration-coordinate model of the center was considered, and its energy parameters were determined. It was concluded that this center was not simply DX-like, but was a true DX center; with a shallow donor and 2 deep negative-U states.

DX Centers in Ionic Semiconductor CdF2:Ga. A.I.Ryskin, A.S.Shcheulin, D.E.Onopko: Physical Review Letters, 1998, 80[13], 2949–52