Growth kinetics and morphology of high quality AlN grown on Si(111) by plasma-assisted molecular beam epitaxy

AlN layers were grown on Si(111) substrates by plasma-assisted molecular beam epitaxy. Crystal quality was assessed by atomic force microscopy and high resolution x-ray diffraction. The III/V ratio and the growth temperature, rather than thickness and growth rate, are found to be critical parameters to achieve good quality AlN layers. III/V ratios close to stoichiometry, and high growth temperatures (⩾900 °C) lead to optimal AlN layers. The growth rate is barely modified when growth temperature changes from 780 to 920 °C, but the growth mode and surface roughness are strongly affected. Optimal AlN layers have full-widths at half-maximum values of 10 arcmin, and an average surface roughness of 48 Å.