Effect of temperature and carrier gas on the properties of thick InxAl1-xN layer

Abstract Thick (>150 nm) I n x A l 1 - x N layers were grown on GaN/sapphire (0 0 0 1) by organometallic vapor phase epitaxy. Growth temperature of I n x A l 1 - x N layers was reduced from 790 to 730 °C, to examine the effects of growth temperature in I n x A l 1 - x N layers grown under H 2 carrier gas. Indium incorporation, surface morphology, electrical, and optical properties of I n x A l 1 - x N 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 I n x A l 1 - x N layers at the expense of surface roughness. Unstrained I n x A l 1 - x N layer was achieved at 730 °C under H 2 carrier gas with x  = 0.18. However, I n x A l 1 - x N layer grown under N 2 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 I n x A l 1 - x N. Edge threading dislocations density is found to be the most important parameter in deciding the characteristics of an I n x A l 1 - x N layer.