Growth of gallium nitride thin films by electron cyclotron resonance microwave plasma-assisted molecular beam epitaxy

Abstract

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 α plane (112̄0) parallel to the R plane of sapphire (101̄2) were grown with the substrate held at 400–700 °C. All films were found to be n type with carrier concentrations varying between 1017 and 1019 cm−3. Films grown at 600 °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.