AlN film deposition as a semiconductor device

Abstract

AlN films were deposited by pulsed laser deposition (PLD) using an Nd: YAG laser (λ = 1064 nm). The films were deposited in a nitrogen atmosphere as working gas; the cathode was an aluminium high purity (99.99%) target. The films were deposited using 7 J/cm2 laser fluence for 10 minutes on silicon (100) substrates. The working pressure was 9×10-3 mbar and the substrate temperature was varied from 200°C to 630°C. The thickness measured by profilometer was 150 nm for all films. Moreover, surface acoustic wave (SAW) devices with a Mo/AlN/Si configuration have been fabricated using AlN-buffer and Mo Channel. The films' morphology and composition were studied using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), respectively. The films' optical reflectance spectra and colour coordinates were obtained by optical spectral reflectometry in the 400-900 cm-1 range using an Ocean Optics 2000 spectrophotometer. The present work found clear dependence on morphological properties, reflectance, dominant wavelength colour purity, frequency response and acoustic wave speed in terms of the temperature applied to the substrate. About 30% reduction in reflectance was observed and increased acoustic wave speed of about 1.3% when the temperature was increased from 200°C to 630°C.