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 C+-implanted AlN films with C+ doses of 5×1016 (AlN:C5×1016) and 2×1017 cm−2 (AlN:C2×1017). AlN:C2×1017 exhibits a saturation magnetization of ∼0.104 emu/g, nearly 1.5 times that of AlN:C5×1016. X-ray diffraction and X-ray photoelectron spectroscopy (XPS) measurements reveal that the implanted 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 C+-implanted AlN films. First-principles calculations indicate that the ferromagnetism in AlN:C5×1016 and AlN:C2×1017 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.