Impact of Plasma-Induced Surface Damage on the Photoelectrochemical Properties of GaN Pillars Fabricated by Dry Etching

摘要

n-GaN pillar photoanodes are fabricated by dry etching of a planar GaN epilayer. The increased surface area results in a plateau photocurrent enhancement of 84%. However, surface damage is introduced during dry etching. In this work, the surface damage is controlled by the RF chuck power. The GaN pillars fabricated using the lowest RF power show a similar current onset potential and current—potential slope as the planar GaN. In addition, the damaged GaN surface of the pillars can be removed in NaOH solution, which leads to the plateau current enhancement of 100% and the onset potential shifts —60 mV with respect to planar GaN. A pair of anodic and cathodic peaks is found in the dark cyclic voltammogram of the damaged pillars, which indicates the charging and discharging of the deep-level traps existing at 0.6 eV below the CB edge.