Growth and characterization of GaN PiN rectifiers on free-standing GaN

GaN PiN rectifiers with high structural quality were grown on free-standing GaN substrates using metalorganic chemical vapor deposition. The lattice mismatch between the substrate and the epitaxial GaN was found to be similar to 1x10(-4). The full width at half maximum of the (0002) rocking curve was 79 arcs compared to 230 arcs for similar materials grown on sapphire. The incorporation of C, H, and O impurities in the homoepitaxial drift layer was reduced by a factor of 2-4. The rectifiers on GaN demonstrated rectification to -265 V, which represents a 1.6x improvement over the rectifiers on sapphire and corresponds to a critical electric field similar to 2.7 MV/cm. The homoepitaxial rectifiers also showed two orders of magnitude lower reverse leakage and a smaller negative temperature coefficient for breakdown voltage, consistent with a reduced defect density in the drift region. (c) 2005 American Institute of Physics.