Ion beam assisted pulsed laser deposition of epitaxial aluminum nitride thin films on sapphire substrates

Epitaxial aluminum nitride films were grown on c- and r-plane oriented sapp hire substrates by pulsed laser deposition technique. Additionally the infl uence of nitrogen/argon ion bombardment during film growth was studied. By X-ray diffraction measurements only the hexagonal wurzite structure of AIN was found. The epitaxial relationship between film and substrate was invest igated by X-ray diffraction texture measurements. On c-plane oriented sapph ire the wurzite c-axis is perpendicular to the substrate surface. On r-plan e oriented sapphire not only an a-axis orientation but also a tilt of the h exagonal c-axis by 30 degrees off the surface normal has been observed. Ion irradiation can improve epitaxy on c-plane oriented sapphire at a certain energy, depending on the angle of incidence. From the dechanneling dependen ce in Rutherford backscattering spectroscopy channeling spectra defect clus ters, like stacking faults, are considered as dominating defects. (C) 2001 Elsevier Science B.V. All rights reserved.