On the physical models for 7.2 kV AlGaN/GaN SBDs with dual gates: polarization gate and common-connected grooved-gate/anode architecture to suppress leakage current and reduce dynamic resistance

Abstract In this work, with the developed physical models, we systematically investigate the impact of dual gates, i.e., the polarization gate and the common-connected grooved-gate/anode architecture, on the electrical characteristics of lateral AlGaN/GaN Schottky barrier diodes (SBDs). The Al 0.20 Ga 0.80 N layer is inserted into an unintentionally doped GaN layer (u-GaN) as the polarization gate. Negative fixed polarization charges at the GaN/Al 0.20 Ga 0.80 N interface enhance the expansion of depletion region in the u-GaN layer. The polarization gate can also raise the energy barrier for electrons in the u-GaN region. As a result, it significantly suppresses the bulk leakage current and effectively reduces the defect-related dynamic resistance under electrical stress conditions. Additionally, the dual gates can generate an enhanced charge-coupling effect in the u-GaN layer. As a result, the electric field magnitude at the edge of the Schottky contact and field plate is effectively reduced, leading to an increased breakdown voltage (BV). For the grooved-gate structure, the Al 0.25 Ga 0.75 N barrier layer is partially etched, thus hardly influencing two-dimensional electron gas (2DEG) density and specific ON-resistance (R on,sp ). The optimized device design is also conducted by investigating the depth of the grooved gate (D tr ), the thickness of the gate insulator layer (T ox ), the length of the grooved gate field plate (L GFP ), the distance between the gate and the cathode (L GC ), and different insulator materials with various dielectric constants.