Electric-field redistribution via high- k dielectric trench in GaN-on-Si AlGaN/GaN HEMTs

We report a GaN-on-Si AlGaN/GaN high-electron-mobility transistor (HEMT) incorporating a drain-side Pb(Zr,Ti)O3 (PZT) trench for electrostatic field management. The mechanism is formulated using the displacement-field boundary conditions and evaluated by two-dimensional technology computer aided design with a field-independent relative-permittivity sweep from 3.9 to 500. The calculations reveal the nonmonotonic dependence of terminal voltage on permittivity and a broader drain-side high-field distribution for the nominal εr=300 case. Experimentally, a representative PZT-trench HEMT reaches 1405 V at LGD=9 μm, compared with 783 V for a co-fabricated conventional device and 957 V for a previously reported hybrid Schottky–ohmic drain HEMT, corresponding to breakdown-voltage improvements of 79% and 47%, respectively, while retaining a specific ON-resistance of 1.47 mΩ cm2. The dynamic-to-static ON-resistance ratios, RON,dyn/RON,static, are 1.6× and 2.5× after 900 and 1200 V off-state stress, respectively, at a 3 μs extraction delay. These results demonstrate simultaneous enhancement of voltage handling and dynamic performance through drain-side dielectric-boundary engineering.