Preparation of AlN thin films by means of CVD using iodide source under atmospheric pressure

Abstract

AbstractEpitaxial aluminum nitride (AlN) thin films were successfully prepared on the (0001) sapphire substrate by chemical vapor deposition (CVD) using aluminum iodide (AlI3) and ammonia (NH3) under atmospheric pressure at 750 ºC. The crystallographic relationship between AlN thin films and Al2O3 substrate is in the following; AlN(0001)//Al2O3(0001) and AlN[1010]//Al2O3[1120]. Lattice parameters of AlN thin film measured by X-ray diffraction revealed that c=0.498 and a=0.311 nm, respectively. Residual stress estimated by modified sin2ψ method was 0.38 GPa in compressive stress. Cross-sectional TEM observation revealed that an interlayer lies between the AlN films and the sapphire substrate. It was suggested that relaxation of residual stress caused by the mismatching of lattice parameter and thermal expansion coefficient was brought about by the interlayer.