Electronic properties of semiconducting Zn ( Si , Ge , Sn ) N 2 alloys

We report on results of first-principles electronic structure calculations on disordered $\\mathrm{Zn}(\\mathrm{Si},\\mathrm{Ge},\\mathrm{Sn}){\\mathrm{N}}_{2}$ alloys. These calculations on substitutional disordered alloys are carried out using the Korringa-Kohn-Rostoker Green function (KKR-GF) method in combination with the coherent potential approximation (CPA) alloy theory. The band gaps and effective masses as well as the disorder-induced finite lifetime of electronic states at the conduction band minimum and valence band maximum are evaluated by analyzing the Bloch spectral functions. Relativistic effects are found to have a small impact and in particular the influence of the spin-orbit coupling is negligible. The alloys with low Si content show band gaps and effective masses which change almost linearly with the composition. Their relatively small effective mass and long lifetime indicate a high charge carrier mobility.