Tri-Gate Normally-Off AlN/GaN HEMTs With 2.36 W/mm of Power Density and 67.5% Power-Added-Efficiency at V<sub> <i>d</i> </sub> = 12 V
Jingshu Guo, Jiejie Zhu, Siyu Liu, Kai Cheng, Qing Zhu, Pengfei Wang, Kai Liu, Ziyue Zhao, Lingjie Qin, Yuxi Zhou, Minhan Mi, Yue Hao, Xiaohua Ma
Abstract
In this letter, we present high-performance tri-gate normally-off HEMTs RF power devices using MOCVD-grown thin barrier SiN/AlN/GaN heterostructures. The normally-off devices exhibit alloyed Ohmic contact resistance of about <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.35 \Omega \cdot $ </tex-math></inline-formula> mm, low threshold-voltage of 0.2 V, very high output current of 1.61 A/mm, and high peak power added efficiency (PAE) of 67.5% with drain voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${(}{V}_{\text {d}}{)}$ </tex-math></inline-formula> of 12 V and frequency at 3.6 GHz. Owing to the high breakdown voltage of 159 V when gate bias at −4 V, the normally-off device shows a maximum output power of 5.96 W/mm at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {d}}$ </tex-math></inline-formula> = 28 V with a peak PAE of over 50% and gain of over 20 dB. The SiN/AlN/GaN epi-structures and tri-gate normally-off HEMTs demonstrated in this work show promising potential for both low-voltage and high-voltage applications.