Influence of deposition angle on the structural, morphological and optical properties of sputtered AlN thin films

Fabrication of AlN thin films of 90 nm thickness was performed using magnetron sputtering technique at different deposition angles of 0°, 15°, 30°, 45° and 60°. Structural and morphological characteristics of the produced samples were obtained by means of x-ray diffraction (XRD), atomic force microscopy (AFM) and field emission electron microscopy (FESEM) analyses. The spectrophotometry analysis with both s- and p-polarized lights at two incident light angles of 30° and 60° were carried out for obtaining the optical spectra of the samples while Kramers-Kronig method was used for calculation of refractive index and further analysis carried out to obtain energy gaps and absorption peaks. Results showed maximum void fraction and surface roughness for film deposited at 30° consistent with previous publications on oblique angle deposition. The higher the porosity of the AlN films in this work showed lower refractive index and because smaller grains/nanoparticles are produced larger energy band gaps are obtained.