Improved Breakdown Voltage in AlGaN/GaN High Electron Mobility Transistors by Employing Polyimide/Chromium Composite Thin Films as Surface Passivation and High-Permittivity Field Plates

The breakdown voltage of AlGaN/GaN high electron mobility transistors (HEMTs) is enhanced by employing metal chromium (Cr) nanoparticle-embedded polyimide (PI) as a high-permittivity (high-K) dielectric covering both the source-gate and gate-drain regions. The PI/Cr composite high-K dielectrics acting as a field plate prevent the occurrence of strong electric fields produced at the drain side edge of the gate electrode to obtain an optimum lateral electric flux of HEMTs. The breakdown voltage is improved by approximately 35% when using the PI/Cr thin film dielectric field plate while maintaining high performance, a high transconductance value of 122.4 mS/mm, and a large saturated drain-current value of 748 mA/mm.