Effect of growth temperature on the properties of GaN epitaxial films grown on magnesium aluminate scandium oxide substrates by pulsed laser deposition

High-quality GaN epitaxial films have been grown on magnesium aluminate scandium oxide (ScMgAlO4) substrates at low temperature of 450 °C with an in-plane epitaxial relationship of GaN[1-100]//ScMgAlO4[1-100]. It is found that the ~300 nm-thick GaN epitaxial films grown at 450 °C show the full-width at half-maximums (FWHMs) for GaN(0002) and GaN (10-12) of 0.18° and 0.40°, respectively, and very smooth surface with a root-mean-square (RMS) surface roughness of 1.5 nm. There is no interfacial layer existing between GaN and ScMgAlO4. However, as the growth temperature increases, the crystalline quality, surface morphology, and interfacial properties of as-grown GaN epitaxial films are deteriorated gradually. These GaN epitaxial films are of great importance for the fabrication of highly-efficient GaN-based devices.