AB-INITIO STUDY OF ANOMALOUS BAND-GAP BOWING IN GAAS1-XNX ALLOYS

A full potential self-consistent linear muffin-tin orbital method in t he local density approximation (LDA) has been employed to investigate the electronic structure of the 14 ordered GaAs1-xNx alloys with x = 0 .0, 0.037, 0.074, 0.111, 0.125, 0.25, 0.375, 0.407, 0.50, 0.625. 0.75, 0.875, 0.963 and 1.0. The lattice parameter is seen to have a non-lin ear variation with the concentration of the constituent atoms. In LDA, a near closure of the fundamental energy gap appears in the concentra tion range 12.5-62.5% of N atoms. A strong hybridization of N s states with the Ga (s,p) and As (s,p) states is seen at the bottom of the co nduction band and these stares descend into the fundamental gap, filli ng it ei:her partially or completely. The band gap for the random allo ys also shows an anomalous bowing.