Effect of cation substitution on electronic band structure of ZnGeAs2 pnictides: A mBJLDA approach

► These compounds are characterized as narrow band gap semiconductors with a maximum gap (1.27 eV) for ZnGeAs2. ► A good agreement of band gaps with experiments is obtained within mBJLDA formalism. ► The band gap decreases with the substitution of either one or both cations in reference compound, ZnGeAs2. ► The ionic/covalent character for AAs/BAs bond has been described on the basis of electro-negativity difference of the atoms. ► The d-states of transition metal, Zn are localized deeper in valence band (E < 5 eV), showing no effective role to decide the magnitude of semiconducting band gap.