Advanced SOI-MESFET design with tungsten-oxide and Si3N4 buffering for enhanced breakdown voltage and RF applications

C-MESFETs often suffer from low breakdown voltage, limited output power, and reduced RF efficiency. We propose a TOx-MESFET that reshapes device electrostatics by shifting the gate toward the source, inserting an oxide at the gate edge, and embedding a tungsten layer above the buried oxide while isolating it from the semiconductor with a thin Si 3 N 4 interlayer. This structure redistributes the electric field, suppresses crowding at the gate-drain side, and maintains a wider effective channel under bias, improving both DC robustness and high-frequency performance. Simulations show that breakdown voltage rises from 15.8 to 39.69 V, saturation drain current from 0.168 to 0.182 A/mm, and maximum output power from 0.300 to 0.858 W/mm. RF metrics also improve: F T increases from 19.3 to 25.5 GHz, F max from 80 to 108.18 GHz, current gain from 56.6 to 84.5 dB, MTG from 34.25 to 48.8 dB, GMS from 124 to 170 dB, and U from 15 to 19.45 dB.