Influence of laser fluence and laser repetition rate on the syntheses of aluminium nitride thin films by nitrogen-ion-assisted pulsed laser deposition

Abstract

Aluminium nitride (AlN) thin films have been grown on Si(111) and Al2O3(001) substrates by pulsed KrF excimer laser (wavelength 248 nm, duration 30 ns) ablation of AlN target with assistance of nitrogen ion beam bombardment. The influence of process parameters such as laser fluence and laser repetition rate has been investigated to obtain high quality AlN films. The XRD spectra of AlN films on Si(111) and Al2O3(001) substrates yield full-width-half-maximum (FWHM) values of ∼2.1-1.7°. The chemical composition of the films is characterized by X-ray photoelectron spectroscopy (XPS). The surface morphology of the films is measured by atomic force microscope (AFM). Al2O3(001) substrate shows better matching with the AlN films since highest crystallite size can be achieved among the different type of substrates evaluated. Better quality AlN films (with bigger crystallite size) can be achieved with higher laser fluence of 6 J/cm2 and an optimum laser repetition rate of 7 Hz.