GROWTH OF GALLIUM NITRIDE THIN-FILMS BY ELECTRON-CYCLOTRON RESONANCE MICROWAVE PLASMA-ASSISTED MOLECULAR-BEAM EPITAXY

We report on optimization studies for the growth of GaN films by the electron cyclotron resonance microwave plasma-assisted molecular beam epitaxy (ECR-MBE) method on the R plane of sapphire. The films were grown by the reaction of Ga vapor with ECR-activated molecular nitrogen and their growth kinetics were found to depend strongly on the distance between the ECR condition and the substrate. Single crystalline films with their alpha plane (1120BAR) parallel to the R plane of sapphire (1012BAR) were grown with the substrate held at 400-700-degrees-C. All films were found to be n type with carrier concentrations varying between 10(17) and 10(19) cm-3. Films grown at 600-degrees-C were found to have the smallest amount of strain and the highest electron mobility, suggesting that strain might be one of the sources of compensating defects.