Breakdown Voltage Assessment of GaN HEMT Devices through Physics-Based Modeling

An extensive study is conducted to evaluate breakdown mechanisms in gallium nitride (GaN) high electron mobility transistors (HEMT). A comprehensive physics-based model of a common HEMT provides the base comparison to conduct different material and geometric investigations. The variations are evaluated in a progression toward the optimal configuration: 1) varying the passivation material, 2) replacing the substrate material, 3) reducing the doping profile along the GaN and aluminum nitride (AlGaN) layers and 4) a field plate (FP) addition. The electric field distribution across the source, gate, and drain is analyzed for each case as well as their I-V curves until the breakdown voltage (BV). The best results are revealed under the FP case.