Electronic band structure of II-VI quaternary alloys in a tight-binding approach

Based on a successful description of the band gap change with composition for the II-VI ternary alloys, we describe a method to set up tight-binding Hamiltonians for quaternary alloys. We use a formula that can be thought as a straightforward generalization of the virtual crystal approximation for this case. In this work we consider Zn1-yCdySe1-xTex and study the change of the band gap with composition obtained by direct diagonalization of the corresponding Hamiltonians. We next consider the technological interesting compound Zn1-yCdyS1-xSex. The agreement with the experimental data is remarkable.