Band Structures of GaAs1−xPx and In1−xGaxP

The band structures of GaAs 1− x and In 1− x Ga x P are calculated in the virtual crystal approximation using the empirical pseudopotential method. The effects of disorder and of spin‐orbit coupling are neglected. The lattice parameter is assumed to vary linearly with the mole fraction of one compound x and the six non‐zero pseudopotential form factors V j ( x ) ( j = 1 to 6) are assumed to vary as Vj ( x ) = V j ( 0 ) + ( V j (1) – V j (0)) × ((1 ‐ α) x + α x 2 ), where α is a constant independent of j . It is found that the calculated bowing parameter of the lowest direct band gap E 0 (γ v 15 ‐ γ c 1 ) varies linearly with α, and this enables a value for α to be found. Results are presented for the bowing parameters of the indirect gaps, and for the values of x at which two of the gaps become equal. Graphs of the variation of effective masses with x are also given. The results indicate that, contrary to what has been reported in the literature, the empirical pseudopotential method is applicable to alloy systems.