A novel symmetrical 4H-SiC MESFET: an effective way to improve the breakdown voltage

摘要

In this paper, a novel symmetrical structure (SS) of 4H-SiC metal semiconductor field effect transistor (MESFET) as an effective way to improve the breakdown voltage is presented. The key idea in this work is to improve the breakdown voltage, maximum output power density, and frequency parameters of the device using a symmetrical structure with recessed gate. The SS-MESFET modifies the electric field in the drift layer significantly. The influence of the SS-MESFET on the saturation current, breakdown voltage (V-BR), and small-signal characteristics of the SS-MESFET are studied by numerical device simulation. Using two-dimensional device simulation, we demonstrate that the breakdown voltage (V-BR) improved by factors 2.5 and 3.3 in comparison with an asymmetrical conventional MESFET structure (AC-MESFET) and a symmetrical conventional MESFET structure (SC-MESFET), respectively. Also, the maximum output power density (P-max) improved about by 93 and 250 % in comparison with the AC-MESFET and SC-MESFET structures, respectively. So, the SS-MESFET shows the superior maximum available gain (MAG), unilateral power gain (U), and current gain (h(12)) which is presenting the proposed structure is more suitable device for high power microwave applications.