HIGH-QUALITY GAN HETEROEPITAXIAL FILMS GROWN BY METALORGANIC CHEMICAL-VAPOR-DEPOSITION

In this paper, we describe the growth and characterization of high-qua lity GaN heteroepitaxial films grown on basal-plane sapphire substrate s using metalorganic chemical vapor deposition. The quality of these f ilms is analyzed by a variety of methods, including high-resolution x- ray diffraction, optical transmission spectroscopy, transmission elect ron microscopy (TEM), room-temperature photoluminescence, and room-tem perature Hall measurements. The x-ray diffraction full width at half m aximum value of Delta Theta similar to 37 arc s is the narrowest repor ted to date for any III-V nitride film on any substrate. The x-ray roc king curves for similar to 0.48 mu m thick GaN/Al2O3 heteroepitaxial l ayers exhibit Pendellosung fringes, indicating that even relatively th in films can be of high quality. High-resolution TEM lattice images fu rther attest to the excellent structural quality, showing the films to be completely free of stacking faults. Furthermore, no evidence of co lumnar growth is observed.