Simulation design of high Baliga's figure of merit normally-off P[sbnd]GaN gate AlGaN/GaN heterostructure field effect transistors with junction field plates

Abstract

In this paper, we conducted a numerical analysis on novel Normally-off PGaN gate AlGaN/GaN heterostructure field effect transistors with junction field plates (JFP-HFET). The breakdown voltage (BV) was significantly improved with the introduction of the junction field plate (JFP), which can make a rectangular distribution of the electric field in the GaN channel between the gate and the drain. The highest BV of 1340 V of JFP-HFET could be achieved with the gate to the drain distance Lgd = 6 μm, the length of the P-type region of the JFP Lp = 5.8 μm, the thickness of the JFP Tj = 500 nm, the doping concentration of P-type region of the JFP Np = 1 × 1017 cm−3, and the Al fraction of the AlGaN JFP xAl = 0.25. The optimum parameters of the JFP-HFET were achieved by considering both the principle of charge balance and the practical fabrication of the III-V devices. The highest Baliga's figure of merit (BFOM) 1.2 GW/cm2 was obtained under the conditions of Lgd = 6 μm, Lp = 5.8 μm, Tj = 100 nm, Np = 6 × 1017 cm−3, and xAl = 0.3. CV, turn-on and turn-off processes revealed that the JFP-HFET showed better switching characteristics than that of the HFET with metal field plate.