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

TL;DR

This study investigates how nitrogen flow rate affects the structural, electronic, and surface properties of DC magnetron sputtered nitrogen-rich AlN thin films, revealing changes in crystallinity, density, and vibrational modes.

Contribution

It provides new insights into the relationship between nitrogen flow rate and the atomic coordination, phonon vibrations, and surface composition of AlN thin films.

Findings

Increased N2 flow enhances c-axis orientation and film density.

N K-edge spectroscopy reveals hybridization and coordination changes.

Oxygen incorporation affects vibrational modes in Raman spectra.

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 3.18g/cm3 for 40% N2. The transition of electrons from N 1s to 2p states hybridized with Al 3p states because of {\pi}* 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 15.97at.% Al, N and O respectively. Blue-shifting of A1(LO) and E1(LO) modes in the Raman spectra at phonon energies 800 and 1051cm-1 respectively was most likely due to the presence of oxygen bonds in the AlN films.