Material properties of GaN grown by radio frequency plasma-assisted molecular beam epitaxy on Si (111) substrates

GaN films were grown on Si (111) substrates by nitrogen rf plasma source molecular beam epitaxy. Reflection high-energy diffraction (RHEED), atomic force microscopy, infrared transmittance and photoluminescence results characterized the properties of GaN films grown under different in-situ substrate preparation and growth initiation methods. Very smooth surfaces, exhibiting surface reconstruction in RHEED, were achieved by using all AIN buffer layer. However, these films produced weak photoluminescence, compared to that of the GaN layers directly deposited on a reconstructed 7x7 Si (111) surface.