REVISED CALCULATION OF POINT-DEFECT EQUILIBRIA AND NONSTOICHIOMETRY IN GALLIUM-ARSENIDE

From an analysis of relevant published literature, it is deduced that the dominant disorder in GaAs is Frenkel defect formation on the arsenic sub-lattice with the arsenic vacancy exhibiting donor-like behaviour at high temperatures. Standard methods of chemical thermodynamics are used to derive expressions for the concentrations of the neutral and charged point defects. Mass action constants are obtained from a combination of a priori estimates and fitting to experimental data. The phase extent of GaAs is mapped and the model shown to account adequately for the density, lattice parameter and internal friction variations in as-grown and heat treated material as well as for the high temperature Hall coefficient behaviour. © 1979.