Physical insights into the reliability of sunken source connected field plate GaN HEMTs for mm-wave applications

This article investigates the incorporation of field plates in AlGaN/GaN High Electron Mobility Transistors (HEMTs) which leading to enhancement in the device breakdown voltage and a reduction in the reverse leakage current. Using Atlas TCAD software breakdown behavior of gate-connected field plate (GFP), gate-source (dual) field plate, and discrete source-connected field plate (Sunken SC-FP) designs with field plate length variation is probed and physical insight is developed through electric field profile, and impact ionization contour plots. By employing a Sunken SC-FP with gate length of 0.4 μm in the gate-drain access region the device breakdown voltage is improved and has high JFOM (4.8 THz·V). Also, on-resistance (RON) degradation is minimum in the Sunken SCFP (20.12 %), compared with GFP (31.20 %) and dual FP (24.96 %) architectures, when the device is stressed in the off-state (VGS = −40 V) for 1 min. The RF performance of the Sunken SC-FP HEMT is studied using small signal parameters and the load pull measurements as a function of drain bias.