Effect of temperature and carrier gas on the properties of thick [formula omitted]N layer

Abstract

Thick (>150 nm) InxAl1-xN layers were grown on GaN/sapphire (0 0 0 1) by organometallic vapor phase epitaxy. Growth temperature of InxAl1-xN layers was reduced from 790 to 730 °C, to examine the effects of growth temperature in InxAl1-xN layers grown under H2 carrier gas. Indium incorporation, surface morphology, electrical, and optical properties of InxAl1-xN layers were examined as a function of growth temperature. Increase in In-molar fraction, as determined by high resolution X-ray diffraction, was observed with decreasing growth temperature of InxAl1-xN layers at the expense of surface roughness. Unstrained InxAl1-xN layer was achieved at 730 °C under H2 carrier gas with x = 0.18. However, InxAl1-xN layer grown under N2 carrier gas at 730 °C to study the effects of carrier gas, was observed with two times higher In-molar fraction (x = 0.37) and one order lower carrier concentration. This work shows the essential requirement of a multi-characterization approach to establish a connection between structural, electrical, and optical properties to improve our understanding towards InxAl1-xN. Edge threading dislocations density is found to be the most important parameter in deciding the characteristics of an InxAl1-xN layer.