High efficiency 100-nm-sized InGaN/GaN active region fabricated by neutral-beam-etching and GaN regrowth for directional micro-LED

The influence of regrown GaN on the optical properties of neutral-beam-etched (NBE) nanodisk of InGaN/GaN multiple quantum wells (MQWs) was investigated by excitation-power-dependent photoluminescence (PL) at 5 and 295 K. After regrowth of GaN, the PL peak of nanodisk at both 5 and 295 K increases to a higher energy position by about 40 meV, due to the relaxation of stress in MQWs. The internal quantum efficiency (IQE) of nanodisk after regrowth was increased by 400% 50%, depending on the excitation power. The significantly enhanced IQE and its stability over the whole range of excitation power clearly indicate a successful regrowth of GaN on the InGaN/GaN nnaodisk with a high interface quality. These results can offer considerable insight into the regrowth of GaN on NBE nanodisk towards directional micro-LED in top-down structure.