CALCULATION OF THE HEAT OF FORMATION OF TERNARY COMPOUNDS - P-GA-AS, N-GA-AS, N-GA-P

Miedema method, which was proposed to calculate the heat of formation of binary alloy system, is extended for calculating the heat of format ion of ternary system by using the Toop's model: The hypothetical meta llic allotropes correspounding to the properties of nonmetallic elemen ts are introduced. In our calculation, the structure-dependent energy contributions have not been taken into account. The heat of formation of GaAs1-xPx, GaAs1-xNx, and GaP1-xNx are obtained by projecting the h eat of formation of ternary systems, P-Ga-As, N-Ga-As, and N-Ga-P onto the plane of the concentration of Ga, c(2), = 0.5, respectively. The possibility of existence of ordered ternary compound was predicted. Th e dependence of direct band gap, E(Gamma) or indirect one, E(X), for G aP1-xNx and GaAs1-xNx, on x, the concentration of N, is obtained by us ing the dielectric theory of electronegativity.