Growth Mechanism of N-Polar GaN on Vicinal N-Polar AlN Templates in Metal-Organic Vapor Phase Epitaxy

In this study, nitrogen-polar (N-polar) GaN/Al0.9Ga0.1N/aluminum nitride (AlN) structures are grown on a sapphire substrate with an offcut angle of 2.0 degrees from the m axis using metal-organic vapor phase epitaxy. Low-growth temperatures of N-polar GaN result in a shorter Ga-migration length, and 2D GaN growth is successfully achieved. The growth temperature and V/III ratio dependence are investigated for N-polar GaN. As a result, high-quality and flat N-polar GaN is successfully grown at a low temperature of 650 degrees C at a high V/III ratio and nonequilibrium conditions. Through X-ray reciprocal space mapping, N-polar GaN can be grown coherently on a N-polar AlN template at low temperatures around 650 degrees C, relaxing at higher temperatures. N-polar GaN is successfully grown 2D at low temperatures. The optimum V/III ratio depends on the growth temperature, with lower V/III ratios suitable for growth temperatures of 800 degrees C and higher V/III ratios for 650 degrees C. The metal-organic vapor phase epitaxy method shows superiority in the growth of N-polar GaN rather than that of metal-polar GaN.image (c) 2024 WILEY-VCH GmbH