Gate leakage reduction in AlGaN/GaN HEMTs using in situ ion treatment

Abstract

A new in situ treatment method is proposed to reduce the gate leakage in normally-on AlGaN/GaN HEMTs. It consists of O2-Ar ion bombardment before the gate metalization. Ion treatment is found to improve the quality of gate metal and semiconductor interfaces. This process reduces the gate leakage current by around 25 times. The process is validated for wafer level uniformity and temperature dependency against the traditional NH4OH treatment. Ion treated HEMT devices are found to possess two orders of magnitude smaller standard deviations in gate leakage distribution across the wafer. The gate leakage is found to be less dependent on temperature comparatively. The trap energy level of the HEMTs treated using the proposed method is found to be higher than the traditional ones as extracted from Poole-Frenkel electron emission analysis. The new method results in a 0.13 dB improvement in the minimum noise figure of the HEMT on average from DC—16 GHz.