A Comparative Study on Metalorganic Vapor Phase Epitaxial InGaN with Intermediate In Compositions Grown on GaN/Sapphire Template and AlN/Si(111) Substrate

The growth of InGaN with intermediate In compositions on GaN/sapphire template and AlN/Si(111) substrate has been comparatively studied. By using an metalorganic vapor phase epitaxy (MOVPE) system with a horizontal reactor, InGaN films are grown at a temperature of 600–800 °C in the pressure of 150 Torr. By optimizing growth temperature and trimethylindium/(trimethylindium+ triethylgallium) molar ratio, single crystalline InxGa1-xN with x = 0–1 are successfully grown on both substrates. The films grown at a relatively high temperature (≥700 °C) with In compositions of 0.3 or less show phase separation when their thickness exceeds a critical value (0.25–0.4 µm), while the samples grown at 600 °C with In compositions of 0.35–0.5 show no phase separation even if the thickness is increased to 0.7 µm. To evaluate the crystalline quality of grown films, FWHM of X-ray rocking curve (XRC) for InGaN(0002), tilt, is measured. There is no marked difference in tilt data between films grown on GaN/α-Al2O3(0001) and AlN/Si(111). For the samples grown at 600 °C with In contents of 0.35–0.5, tilt data are drastically increased and widely scattered suggesting the existence of important unknown parameters that govern crystalline quality of InGaN grown at a relatively low temperature.