A first-principles study on electronic and optical properties for Zn31-xAlxMgO

Highlights: • The geometrical structures, electronic and various optical properties of pure ZnO and Zn31-xAlxMgO were studied by first-principle calculations, and their relevant microscopic mechanism were discussed. • The change in the bandgap and optical properties of Zn31-xAlxMgO expands its application in the field of semiconductor materials. • The research provides a theoretical basis for the application of Zn31-xAlxMgO in optical and optoelectronic devices. The photoelectric properties of Mg/Al doped ZnO are investigated using the first-principles study. The lattice parameters of Zn_31-xAl_xMgO clearly increased. The calculations are carried out by the constant Mg doping ratio as 3.13% and different concentrations of Al with 0, 3.13%, 6.25%, 9.38% and 12.5%. The corresponding bandgaps are 3.492, 2.994, 2.448, 2.102, 1.988 eV, respectively. It is revealed that the Fermi level shifts upward when the Al concentration exceeds 6.25%. Therefore, Zn₂₇Al₄MgO is beneficial to obtain n-type ZnO with a higher electron concentration than others. Meanwhile, compared with pure ZnO, the imaginary parts of complex dielectric function, absorption, reflectivity and energy loss function of Zn_31-xAl_xMgO (x > 0) exhibit clear red-shifts.