An oxide-diluted magnetic semiconductor: Mn-doped ZnO

Abstract

Epitaxial thin films of an oxide-diluted magnetic semiconductor, Mn-doped ZnO, were fabricated by pulsed-laser deposition technique. Solubility of Mn into ZnO exceeds thermal equilibrium limit as a result of nonequilibrium film growth process. As Mn content is increased, the lattice constants of both a and c axes of wurtzite ${\mathrm{Zn}}_{\text{1−x}}{\mathrm{Mn}}_x\mathrm{O}$ films $\text{(x<0.35)}$ increase and the band gap expands although considerable in-gap absorption develops. Itinerant electrons over ${10}^{19} {\mathrm{cm}}^{\mathrm{-3}}$ can be doped into the ${\mathrm{Zn}}_{\text{1−x}}{\mathrm{Mn}}_x\mathrm{O}$ films by Al doping, in contrast to low carrier density in the other II–VI diluted magnetic semiconductors. The temperature dependence of the resistivity is almost metallic and considerable magnetoresistance is observed at low temperatures.