Electronic band gap of Zn2x(CuIn)1-xX2 solid solution series (X = S, Se, Te)

Abstract The Zn 2 x (CuIn) 1− x X 2 solid solution series with X = S, Se and Te have been investigated concerning variation of the band gap E g with the chemical composition, especially, with regard to the two-phase field (miscibility gap) occuring in all three systems. The band gap E g was determined by diffuse reflection on powder samples of the quaternary alloys. A highly non-linear dependence of E g on the chemical composition was found, which may be caused by the repulsive interactions of Cu3d and anion 3p states. Moreover, the E g value of the ternary end member of the solid solution series is even reached in a composition range x  ∼ 0.45 (X = S), x  ∼ 0.4 (X = Se) and x  ∼ 0.3 (X = Te). This is due to a nearly constant band gap within the small single-phase tetragonal region (0 ≤  x