Correlation Between Optical, Morphological, and Compositional Properties of Aluminum Nitride Thin Films by Pulsed Laser Deposition

Aluminum nitride (AlN) thin films were grown in a N
₂
atmosphere onto a Si/Si
₃
N
₄
substrate by pulsed laser ablation. We have varied the substrate temperature for the thin film growth, using X-ray reflectometry analysis, we have characterized the thickness and density of the thin layer and the interface roughness from the X-ray reflectivity profiles. Experimental data showed that the root-mean-square roughness was in the range of 0.3 nm. The X-ray photoelectron spectroscopy (XPS) was employed to characterize the chemical composition of the films. These measurements detected carbon and oxygen contamination at the surface. In the high-resolution XPS Al2p data, binding energies for Al–N and Al–O species were identified but no Al–Al species were present. In the N1s data, N–O species were not detected, but chemically bonded O was present in the films as Al–O species. Furthermore, the value of optical energy gap,
$E_{g}$
was
$\sim 5.3$
(±0.1) eV. The composition varied with process conditions, and the nitrogen content decreased in AlN films processed above 500 °C.