Effects of high-dose Mn implantation into ZnO grown on sapphire

Abstract

ZnO films grown by pulsed-laser deposition on $c$ -plane ${\mathrm{Al}}_2{\mathrm{O}}_3$ substrates were annealed at temperatures up to $\text{600\hspace{0.05em}°}\mathrm{C}$ to produce $n$ -type carrier concentrations in the range ${\text{7.5×10}}^{15}{\text{–1.5×10}}^{20}\hspace{0.5em}{\mathrm{cm}}^{\text{−3}}.$ After high-dose ${\text{(3×10}}^{16}\hspace{0.5em}{\mathrm{cm}}^{\text{−2}})$ Mn implantation and subsequent annealing at $\text{600\hspace{0.05em}°}\mathrm{C},$ all the films show $n$ -type carrier concentrations in the range ${\text{2–5×10}}^{20}\hspace{0.5em}{\mathrm{cm}}^{\text{−3}}$ and room temperature hysteresis in magnetization loops. The saturation magnetization and coercivity of the implanted single-phase films were both strong functions of the initial anneal temperature, suggesting that carrier concentration alone cannot account for the magnetic properties of ZnO:Mn, and that factors such as crystalline quality and residual defects play a role.