AlGaN/GaN HEMTs With Damage-Free Neutral Beam Etched Gate Recess for High-Performance Millimeter-Wave Applications

Abstract

The electrical performances of gate-recessed AlGaN/GaN high-electron mobility transistors (HEMTs) fabricated using the damage-free neutral beam etching (NBE) method are demonstrated. The NBE method could eliminate the plasma-induced defects generated by irradiating ultraviolet/VUV photons in the conventional inductively coupled plasma reactive ion etching method. The AlGaN/GaN HEMT device fabricated using the new gate recess process exhibited superior electrical performances, including a maximum drain current density (I <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS,max</sub> ) of 1.54 A/mm, low 1/f noise, a current-gain cutoff frequency (fT) of 153 GHz, a maximum frequency of oscillation (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">MAX</sub> ) of 167 GHz, and a minimum noise figure (NF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">min</sub> ) of 3.28 dB with an associated gain (G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">AS</sub> ) of 5.06 dB at 54 GHz. Such superior characteristics confirm the inherent advantages of adopting the damage-free NBE process in fabricating GaN devices for millimeter-wave applications.