Photoenhanced Electrochemical Etching of n-GaN Forced by Negative Bias

Bias-dependent photoenhanced electrochemical etching of n-GaN using CH3COOH solution and KOH solution is described. During etching of n-GaN under an illumination of 90 mW/cm2, n-GaN was etched at a rate of 8 nm/min in 0.04 M of KOH solution, and negligible etching was shown in 1% CH3COOH solution at zero substrate bias. However, n-GaN was successfully etched by applying negative bias, and an etch rate of 286 nm/min resulted from the etching in 1% CH3COOH solution at a bias of -9 V and an illumination intensity of 125 mW/cm2. Etch rate increased with negative bias and illumination intensity for etching in both solutions.