Novel 4H-SiC MESFET with modified depletion region by dual well for high-current applications

Abstract

We describe herein a 4H-SiC metal---semiconductor field-effect transistor (MESFET) with a novel dual well in the buffer layer. The key idea is to change the channel thickness to decrease the hole concentration and modify the depletion region shape and drain current path in the channel. In the proposed structure, a dual well is created in the buffer layer exactly under the gate. We call this structure the dual-well MESFET (DW-MESFET). The drain current of the proposed structure increases by 34.7 % compared with the conventional structure (C-MESFET) due to the change in channel thickness and modification of the depletion region and drain current path. Also, the maximum power density ($$P_{\mathrm{max}}$$Pmax) and the direct-current (DC) transconductance ($$g_{\mathrm{m}}$$gm) of the DW-MESFET increase by 45.23 and 72.5 %, respectively, in comparison with the C-MESFET structure. Hence, the proposed structure can be used for high-current and high-power applications.