GROWTH OF AIN BY METALORGANIC MOLECULAR-BEAM EPITAXY

Thin film AlN has been grown on Al2O3 and GaAs substrates by metalorganic molecular beam epitaxy using amine bonded alane precursors and either tertiarybutylamine or nitrogen from a compact electron cyclotron resonance (ECR) plasma source operating at 2.45 GHz. Typical growth pressures were in the 0.5-1×10-4Torr range. The growth rates, impurity backgrounds, and surface morphologies were examined for both nitrogen sources and both the solid and liquid alanes. In general, growth efficiencies were good for both alane precursors, allowing for deposition of the low temperature, ∼400°C, AlN buffers needed for subsequent growth of GaN and InGaAlN alloys. Low growth temperatures could not be obtained using tertiarybutylamine, presumably due to poor decomposition efficiency of the source at low temperatures. The structural quality of material grown at high temperatures from the ECR plasma was measured by atomic force microscopy, high resolution x-ray diffraction, and transmission electron microscopy, indicating single crystal material with a surface roughness of ∼8 Å and an x-ray full width half-maximum of 430 arcsec. This ECR plasma-derived material was of sufficient quality to allow for the growth of multiple quantum well InGaAlN structures.© 1995 American Institute of Physics.