GaN Film Fabrication by Near-Atmospheric Plasma-Assisted Chemical Vapor Deposition

Abstract

A GaN thin film was fabricated by near-atmospheric plasma-assisted chemical vapor deposition. Pure nitrogen plasma can be generated stably using an alternating pulsed voltage system that applies an alternating pulsed voltage between two parallel-plate electrodes. The excited nitrogen species correspond to the N2 second positive system. An ionic molecular species, which causes film damage, was not observed by optical emission spectrum analysis. Using this plasma as a nitrogen source, the metalorganic chemical vapor deposition of GaN thin film was carried out under a nitrogen partial pressure of 40 kPa and a substrate temperature of 650 °C. The quality of the GaN thin film was examined by two-dimensional X-ray diffraction analysis and X-ray pole figure measurement. These measurements revealed that the film was epitaxial with a 30° rotation of the unit cell with respect to (0001) sapphire in the (0001) basal plane.