Growth and characterization of N-polar GaN films on SiC by metal organic chemical vapor deposition

摘要

Smooth, high-quality N-polar GaN films were grown on C-face SiC substrates by metal organic chemical vapor deposition (MOCVD). Growth on substrates misoriented at 4° toward the m-plane suppressed the formation of hexagonal hillocks commonly observed for the growth of N-polar GaN by MOCVD. Aside from the misorientation, the growth temperature of the initial GaN was observed to have a strong impact on the structural and morphological properties of films grown on vicinal substrates as characterized by x-ray diffraction, atomic force microscopy, photoluminescence, and transmission electron microscopy. This strong temperature dependence was discovered to be a consequence of the island growth mode of the initial GaN. A two-step process was developed, which resulted in GaN films that exhibited XRD rocking curves with a full width at half maximum of 203 arc sec for a (0002) scan and 497 arc sec for a (2021) scan.