Enhancement mode AlGaN/GaN HEMTs by fluorine ion thermal diffusion with high v th stability

Abstract

A method of fluorine ion thermal diffusion has been proposed to realize enhancement-mode AlGaN/GaN HEMTs. By AlF3 solid diffusion source, fluorine ion has successfully diffused in the gate region of AlGaN layer at 800 °C 2 h with a diffusion depth about 20 nm demonstrated by secondary ion mass spectrometry. The fabricated device exhibits a positive threshold voltage of 1.8 V, a drain current density of 95 mA mm-1 at V g = 4 V, a peak transconductance of 50 mS mm-1, a breakdown voltage of 700 V. Besides, the device is also demonstrated with good V th stability under different stress conditions.