1.2-kV Vertical GaN Fin-JFETs: High-Temperature Characteristics and Avalanche Capability
Jingcun Liu, Ming Xiao, Ruizhe Zhang, Subhash Pidaparthi, Hao Cui, Andrew Edwards, Michael D. Craven, Lek Baubutr, Cliff Drowley, Yuhao Zhang
Abstract
This work describes the high-temperature performance and avalanche capability of normally-off 1.2-K V-CLASS vertical gallium nitride (GaN) fin-channel junction field-effect transistors (Fin-JFETs). The GaN Fin-JFETs were fabricated by NexGen Power Systems, Inc. on 100-mm GaN-on-GaN wafers. The threshold voltage ( V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text TH</sub> ) is over 2 V with less than 0.15 V shift from 25 °C to 200 °C. The specific ON-resistance ( R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> \scriptscriptstyle ON</sub> ) increases from 0.82 at 25 °C to 1.8 \textmΩ·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 200 °C. The thermal stability of V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text TH</sub> and R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> \scriptscriptstyle ON</sub> are superior to the values reported in SiC MOSFETs and JFETs. At 200 °C, the gate leakage and drain leakage currents remain below 100 μ\textA at -7-V gate bias and 1200-V drain bias, respectively. The gate leakage current mechanism is consistent with carrier hopping across the lateral p-n junction. The high-bias drain leakage current can be well described by the Poole-Frenkel (PF) emission model. An avalanche breakdown voltage ( BV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text AVA</sub> ) with positive temperature coefficient is shown in both the quasi-static I- V sweep and the unclamped inductive switching (UIS) tests. The UIS tests also reveal a BV <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text AVA</sub> over 1700 V and a critical avalanche energy ( E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text AVA</sub> ) of 7.44 J/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , with the E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\text AVA</sub> comparable to that of state-of-the-art SiC MOSFETs. These results show the great potentials of vertical GaN Fin-JFETs for medium-voltage power electronics applications.