LAUSR

Abstract In the present work, the effect of residual oxygen during reactive sputtering of Al target in a dilute nitrogen environment has been investigated. We have deposited a thin film by reactive sputtering of high purity Al target (99.999%) using a mixture of ultra-high pure Ar & N2 gas in a percentage ratio of 95% and 5%, respectively. The characterization of as-deposited film using Grazing Incidence X-ray Diffraction (GIXRD), X-ray Photoelectron Spectroscopy (XPS), and Energy-Dispersive X-ray (EDX) spectroscopy reveals that in dilute nitrogen environment Al preferred to react with residual oxygen to form amorphous Al2O3 (a-Al2O3) along with aluminum vacancies (AlV). The dilute nitrogen incorporated in the film occupies the AlV sites in Al2O3 and bonded with nearby oxygen to form Al(NOy)x phase. The bulk of the film mainly consists of Al(NOy)x phase, which decreases as we move towards the film surface. At close to the film surface the oxygen vacancies are significantly present. Magnetic and electrical transport properties measurement of the film shows room temperature (RT) magnetism along with n-type semiconducting behaviour. The origin of RT magnetism and observed transport properties have been investigated using a first-principle calculation based on density functional theory (DFT). The residual oxygen driven defects present in the film are found to play a critical role and discussed in detail. The current study is significant in the sense that it provides a new insight to explore the potentials of Al-N-O alloy-based materials as an n-type magnetic semiconductor at room temperature by manipulating defects and optimizing nitrogen concentration.