First-principles investigation of size-dependent piezoelectric properties of bare ZnO and ZnO/MgO core-shell nanowires

Using first-principles density functional theory (DFT) calculations, we evaluate and compare the piezoelectric properties in bare ZnO and ZnO/MgO core-shell nanowires. The study confirms that effective piezoelectric coefficient in bare ZnO nanowires is a highly diameter sensitive parameter. In the thinnest ZnO nanowire, with only one layer of atoms, the effective piezoelectric coefficient attains a maximum value of 12.21 C/m(2). On the other hand, for the first time, we report that piezoelectricity in MgO-passivated ZnO nanowires exhibits a lesser size dependence than in the bare ones, a finding that may prove useful in the design of emerging ultraviolet optoelectronic devices.