First-principles total-energy pseudopotential calculations were used to study the so-called negative-U large lattice relaxation model for column-III and VII donors. The calculated binding energies of DX centers for Al, Ga, In, Cl, Br, and I donor impurities in CdTe were in good agreement with experimental data. Three distinct types of DX-like structure, characterized by either bond rupture or bond compression, were found for column-VII donors. The relative stabilities of these structures were impurity- and pressure-dependent. Only Ga gave rise to a stable DX center in CdTe. Three types of DX center were suggested for column-VII donors. The DX structure became stable at high pressures while, in the alloys, DX1 or DX3 structures were more stable than DX2.

C.H.Park, D.J.Chadi: Physical Review B, 1995, 52[16], 11884-90