Plasma-Induced Damage and Recovery on Au/n-GaN Schottky Diode in Different Processes

The effects of plasma-induced damage on deep traps in n-GaN have been investigated using current–voltage (I–V), capacitance–voltage (C–V), and photocapacitance (PHCAP) measurements. The Au/n-GaN Schottky barrier diodes were fabricated in an inductively coupled plasma ion etching (ICP-RIE) system. After mesa etching to achieve ohmic contact, the n-GaN surface, at which Schottky contacts are fabricated, is etched ∼100 nm by ICP-RIE with various Cl₂/Ar ratios and RIE bias powers (P_B), to introduce plasma damage. The electrical properties of the fabricated Shottky barrier diodes (SBDs) strongly dependent on the RIE gas composition and the bias power P_B applied to the sample stage. In order to overcome the residue and plasma damage on the Schottky area, the samples were treated with HCl at 110 °C for 30 min. Several deep levels (1.8, 2.5, and 3.0 eV below the conduction band) were detected by PHCAP measurement. Improved electrical characteristics were achieved as a result of the HCl treatment and sintering process. The PHCAP measurement results also revealed the effectiveness of thermal and chemical treatments.