علی نادری

In this paper, a new structure for silicon on insulator (SOI) metal semiconductor field effect transistor (MESFET) is proposed. This new structure improves DC and RF characteristics of the device by embedding a region of hafnium oxide which is shaped like a reversed T letter in the channel region. This structure is named SOI-MESFET with T-Shaped oxide part (TSOP). Hafnium oxide region increases the breakdown voltage of the device due to its higher critical electric field in comparison with silicon used in the conventional structure (C-SOI MESFET). The breakdown voltage of the conventional structure is 14 V while it raises to 19.5 V in proposed structure. Furthermore, placing this region in the channel, increases the operating frequencies of the device due to the modification in capacitances. Studying the maximum output power density shows that the proposed structure causes 31.5% improvement compared with the C-SOI MESFET. To improve the device performance, dimensions of the oxide region have been optimized and the more optimum performance achieved by varying the dimensions and finding the most suitable values. Due to the mentioned superiorities of the proposed structure over its conventional counterpart, it can be said that the proposed structure has the capability to be used as a reliable alternative for C-SOI MESFET in high voltage and high frequency applications. Also, from fabrication point of view, a fabrication process flow for T-SOP structure is proposed which shows convenient steps to develop this device.