Etching Characteristics of Hydrogen Environment Anisotropic Thermal Etching for GaN‐Based Functional Photonic Devices

InGaN/GaN‐based group‐III nitride semiconductors are the most promising candidate materials for highly functional active photonic devices in the visible region. Low‐damage nanoscale high‐precision etching with vertical facets is important for realizing photonic crystal (PhC) and optically integrated devices. Herein, the etching characteristics of GaN nanoholes using the hydrogen environment anisotropic thermal etching (HEATE) method, which is based on the hydrogen‐assisted thermal decomposition of GaN, are systematically demonstrated. It is found that high‐precision and vertical nanofabrication is possible at high etching temperature (≈1000 °C) and low hydrogen pressure conditions (<18 Pa). In GaN‐based visible topological PhCs composed of fine triangular nanoholes fabricated under these conditions, the photonic bands are observed to be in good agreement with the three‐dimensional finite‐difference time‐domain simulations, indicating the effectiveness of the HEATE method.