Tailoring the band gap of ZnO/MgZnO coaxial nanowires by the size and the component of Mg

Abstract

Based on first principles calculations, we investigate the changes of the band gaps of wurtzite ZnO/Mg_xZn_1−xO coaxial nanowires by varying the size and Mg components. Our findings show that the band gaps of the concerned nanowires are tunable in different ways: the size of the shell (or the core) dominantly induces a band offset of the conduction band minimum, while the Mg concentration in the shell mainly causes a band offset of the valence band maximum. Statistic analysis reveals that such size- and Mg-component dependent band gaps are tightly correlated with enhanced hybridization between Zn and O induced by the Mg atoms in the shell.