A novel 4H–SiC MESFET with modified channel depletion region for high power and high frequency applications

Abstract

In this paper, a novel 4H–SiC metal semiconductor field effect transistor (MESFET) with modified depletion region is introduced. The key idea in this work is modifying the depletion region in the channel for improving the electrical performances. The proposed structure consists of upper and lower gates. Also, the lower gate is divided into a number (N) of smaller step-shaped sections. Therefore, we have called the proposed structure multiple-recessed 4H–SiC MESFET (MR-MESFET). DC and RF characteristics of the MR-MESFET structure with various lower gate segments are analyzed by 2D numerical simulation. The simulated results show that as the number of the lower gate sections increases, the channel depletion region is modified and the drain current ( I D) enhances. Also, by increasing the number of the lower gate sections, the breakdown voltage ( V BR) enhances, too. Improvement of the I D and V BR leads to a further increase in the output power density of the device. Also, cut-off frequency ( f T), maximum oscillation frequency ( f max), and maximum available gain (MAG) improvements are achieved for the MR-MESFET structure with further number of the lower gate sections. The results show that the MR-MESFET structure with higher number of the lower gate segments has superior electrical characteristics and performances in comparison with the MR-MESFET structure with fewer number of the lower gate sections.