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

摘要

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 N_2 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℃. 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.