Wet etching for isolation of N-polar GaN HEMT structure by electrodeless photo-assisted electrochemical reaction

Electrodeless photo-assisted electrochemical etching was performed in an N-polar GaN high-electron-mobility transistor to obtain device isolation with a flat wet etching surface. The root mean square roughness of the surface after 30 nm etching was 3.4 nm, and a relatively flat etched surface was confirmed. The resistance between the electrodes changed from around 10 2 Ω to approximately 10 8 Ω by 30 nm etching.