Tuning of ferromagnetic behavior of GaN films by N ion implantation: An experimental and first principle-based study

Magnetic properties of N-ion implanted GaN films (150 nm) have been reported. It is found that GaN films grown by the MOCVD technique show strong room temperature ferromagnetic behavior, which can be tuned by implanting N-ions at different fluences (1 x 10(15) to 5 x 10(16) ions-cm(-2)). Presence of implanted N at interstitial sites of the GaN host matrix is indicated from the strain observed in GaN by analysis of XRD data. PL spectra show presence of different types of defects in the as deposited film and engineering of defects after N-ion implantation. XPS spectra of Ga 3d-core level and valence band reveal the bonding of implanted N with the host Ga and/or N. The origin of ferromagnetic behavior is ascribed to unpaired electrons created at N sites due to Ga vacancies. First principle-based calculations also confirm ferromagnetism due to Ga vacancies and the reduction of magnetic behavior in Ga deficient GaN with N-ion implantation at interstitial site. The systematic reduction in the saturation magnetic moment value after N-ion implantation is explained on the basis of pairing of the unpaired electrons due to the bond formation of interstitial N with Ga and N present in the host matrix.

Automated summary

N-ion implanted GaN films exhibit tunable room temperature ferromagnetic behavior, with the presence of implanted N observed at interstitial sites of the GaN host matrix resulting in strain in the film. XRD analysis shows the strain, while PL spectra reveal defect engineering post N-ion implantation. XPS spectra further confirm bonding of implanted N with the host Ga and/or N, leading to the origin of ferromagnetic behavior due to unpaired electrons at N sites caused by Ga vacancies.