An amended structure of metal–semiconductor field effect transistor (MESFET) in SOI technology is presented. In the proposed structure, there is a layer of SiO2 below the gate metal in the channel area. Another oxide layer is embedded in channel region next to the source region. Two layers of oxide (TLO) have been added to the channel area, hence the proposed structure is called TLO-SOI MESFET. Two-dimensional simulation shows that using oxide in the channel area has caused the device to experience 44% improvement in the breakdown voltage. Also, frequency characteristics such as maximum oscillation frequency and cut-off frequency are improved from 81.1 and 19.49 GHz in the basic device to 84.91 and 24.13 GHz in TLO structure, respectively. The other characteristics including maximum output power density, maximum available gain (MAG), unilateral power gain (U), and current gain (H21), are enhanced by about 109%, 24%, 26%, and 56%, respectively.
