Nitrogen flow rate dependent atomic coordination, phonon vibration and surface analysis of DC magnetron sputtered nitrogen rich-AlN thin films

Abstract

In this work, the effect on crystallite orientation, surface morphology, fractal geometry, structural coordination and electronic environment of DC magnetron sputtered AlN films were investigated. X-ray diffraction results disclosed that the c-axis orientation of AlN films increased with the preferred wurtzite hexagonal structure above 17% N2 flow. X-ray reflectivity data confirmed AlN film density increased with increasing N2 flow and was found to be 3.18 g/cm3 for 40% N2. The transition of electrons from N 1s to 2p states hybridized with Al 3p states because of π* resonance was obtained from X-ray absorption spectroscopy of the N K-edge. The semi-empirical coordination geometry of nitrogen atoms has been studied by deconvolution of N K-edge. The surface composition of AlN films at 40% N2 consists of 32.08, 51.94 and 15.97 at.% Al, N and O respectively. Blue-shifting of A1(LO) and E1(LO) modes in the Raman spectra at phonon energies 800 and 1051 cm−1 respectively was most likely due to the presence of oxygen bonds in the AlN films.