Elimination of V‐Shaped Pits in Thick InGaN Layers via Ammonia‐Assisted Face‐to‐Face Annealing

InGaN, a group‐III nitride semiconductor, is expected to be widely used in the field of optoelectronics, owing to its excellent physical properties. However, InGaN has various limitations. This study reports face‐to‐face annealing (FFA) using vapor‐phase and in‐plane mass transport to improve the surface flatness of an InGaN template. InGaN layers are grown on a GaN template that is grown on a c‐plane sapphire substrate using metal–organic vapor‐phase epitaxy. NH₃‐assisted FFA is performed at 1050 °C for 20 min, causing V‐pits to vanish from the InGaN template despite their initial density of 3.3 × 10⁸ cm⁻². The surface condition of the lower InGaN layer is worse than that of the upper InGaN layer due to the FFA‐induced upward mass transport from the lower layer, thereby eliminating the V‐pits. Compositional analysis of the upper layer through Auger electron spectroscopy and energy‐dispersive X‐ray spectroscopy reveals In peaks despite high‐temperature annealing, thus confirming the presence of InGaN. The results of this study offer possibilities for future InGaN crystal growth and InGaN‐based device fabrication.