Optimizing SOI-MESFET transistor performance at high frequencies by air-oxide layers in the channel and a nickel layer in the box

Abstract

In this paper, we introduce a new transistor structure that has improved alternating current and direct current parameters compared to the basic structure. The cutoff frequency of the proposed structure is 33 GHz, while the cutoff frequency of the basic structure is 25.5 GHz. One important improvement is that the gate-drain parasitic capacitors in the channel area are nearly zero, thanks to the presence of an air layer between the gate and source electrodes and a nickle layer in the burried oxide. In addition to the alternating current parameters, the direct current parameters have also been strengthened. The maximum output power density for the new structure is 1.08 W/mm, compared to 0.455 W/mm for the normal structure. Furthermore, the breakdown voltage in the new structure has increased to 30 V, while the basic structure has a breakdown voltage of 16 V. These improvements are attributed to the transfer of the gate to the source and the increased distance from the drain region, as well as the presence of two layers of oxide and air on both sides of the gate. Consequently, the new structure can effectively operate at high voltages and powers.