Room-temperature ferromagnetism in C+-implanted AlN films

Abstract

Diluted magnetic semiconductors (DMSs) have numerous potential applications, particularly in spintronics. Therefore, the search for advanced DMSs has been a critical task for a long time. In this work, room-temperature ferromagnetism is observed in the ${\mathrm{C}}^{+}$ -implanted AlN films with ${\mathrm{C}}^{+}$ doses of $5\times {10}^{16}$ ($\text{AlN}:{\mathrm{C}}_{5\times {10}^{16}}$ ) and $2\times {10}^{17}\hspace{0.17em}{\text{cm}}^{-2}$ ($\text{AlN}:{\mathrm{C}}_{2\times {10}^{17}}$ ). $\mathrm{AlN}:{\mathrm{C}}_{2\times {10}^{17}}$ exhibits a saturation magnetization of ∼0.104 emu/g, nearly 1.5 times that of $\text{AlN}:{\mathrm{C}}_{5\times {10}^{16}}$ . X-ray diffraction and X-ray photoelectron spectroscopy (XPS) measurements reveal that the implanted ${\mathrm{C}}^{+}$ ions occupy the interstitial lattice sites and substitute at the sites of Al atoms. XPS and Doppler broadening of positron annihilation radiation measurements demonstrate the existence of the Al-vacancy related defects in the ${\mathrm{C}}^{+}$ -implanted AlN films. First-principles calculations indicate that the ferromagnetism in $\text{AlN}:{\mathrm{C}}_{5\times {10}^{16}}$ and $\text{AlN}:{\mathrm{C}}_{2\times {10}^{17}}$ is mainly originated from defect complexes involving interstitial C atoms and Al vacancies, which have the lowest formation energy among AlN:C defects containing C atoms and Al vacancies. This work provides a feasible route to develop advanced DMSs.