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

Abstract

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 (PB), 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 PB 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.