Effects of a photo-assisted electrochemical etching process removing dry-etching damage in GaN

We investigated the ability of a photo-assisted electrochemical (PEC) etching process to remove the damage that dry etching causes in the near-surface region of GaN samples. The process consists of anodic oxidation of the GaN surface and subsequent dissolution of the oxide with a chemical treatment, and the extent of the PEC reactions depends on the total charge density transferred in them. The PEC process was conducted for samples prepared with various dry-etching conditions followed by fabrication of Schottky barrier diodes (SBDs) and metal-insulatorsemiconductor (MIS) capacitors. The PEC process greatly improved the barrier height, ideality factor, and reverse leakage current of SBDs. Capacitance-voltage measurements of MIS capacitors revealed that the densities of interface states and discrete traps were both reduced by the PEC process. The results obtained here show that the PEC process can remove dry-etching damage from the GaN surface. (C) 2018 The Japan Society of Applied Physics