PREPARATION OF ALUMINUM NITRIDE EPITAXIAL-FILMS BY ELECTRON-CYCLOTRON-RESONANCE DUAL-ION-BEAM SPUTTERING

Aluminum nitride (A1N) thin films have been deposited on (1 $($) over bar$$ 1.2) sapphire by an electron cyclotron resonance (ECR) dual-ion-beam sputtering method. We have thoroughly investigated the dependence of the crystallinity and surface smoothness of the A1N thin film on the assisted conditions and sputtering conditions. The A1N thin film deposited under assisted conditions with the nitrogen ion beam energy and current density of 100 eV and 0.32 mA/cm(2), respectively, and sputtering conditions with the arrival aluminum flux rate to the substrate surface (Al flux rate) and argon (Ar) ion beam energy of 42 Angstrom/min and 800 eV, respectively, is a single-crystal film with a very smooth surface. In order to prepare the epitaxial film, the Ar ion beam energy must be increased according to increases in the Al flux rate, and decreased according to decreases in the Al flux rate.