An oxide-diluted magnetic semiconductor: Mn-doped ZnO

TLDR

Mn solubility in ZnO exceeds equilibrium limits due to nonequilibrium growth. Mn‑doped ZnO thin films were grown epitaxially by pulsed‑laser deposition. Increasing Mn content expands lattice constants and band gap while inducing in‑gap absorption; Al doping raises carrier density above 10¹⁹ cm⁻³, yielding metallic resistivity and pronounced low‑temperature magnetoresistance.

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 Zn1−xMnxO films (x<0.35) increase and the band gap expands although considerable in-gap absorption develops. Itinerant electrons over 1019 cm−3 can be doped into the Zn1−xMnxO 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.