Growth and characterization of amorphous AlN thin films by reactive magnetron sputtering at low temperature

We present the first report of the preparation and characterization of ct-AM films using reactive magnetron sputtering at cryogenic temperature. By comparison, analogous films grown at room temperature were polycrystalline. The films were characterized using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Rutherford Backscattering Spectrometry (RBS), Infrared (IR) Spectroscopy and optical transmission. XRD studies on films grown at room temperature showed diffraction peaks corresponding to (100), (101), (102) and (210) planes. In contrast, no peaks were observed for AIN films formed at liquid nitrogen temperature confirming the amorphous nature of the films. Composition analysis using RES showed the presence of Al and N in similar to 1:1 stoichiometry. The films were highly transparent and the computed bandgaps of alpha-and c-AlN films were 5.90 and 5.89 eV respectively. We also consider the possibilities of wet etching the AlN films in diluted KOH solution and the results are discussed.