Improvement of self-heating effect in a novel nanoscale SOI MOSFET with undoped region: A comprehensive investigation on DC and AC operations

Abstract

The buried oxide in a SOI MOSFET inhibits heat dissipation in the silicon layer due to low thermal conductivity of the oxide and leads to problematic increase in the device lattice temperature. This work reports a new SOI MOSFET with undoped region (UR-SOI) under the source and channel regions in order to reduce self-heating effect (SHE). The structure has well controlled the lattice temperature and also many improvements are obtained because of the embedded undoped region in the suitable place. Improvements such as increased drain current, reduced maximum lattice temperature, reduced bandgap energy variations, higher DC transconductance and lower DC drain conductance and also increased electron mobility are explored. Also important parameters such as SHE characteristic frequency (fth), thermal resistance (Rth) and thermal capacitance (Cth) have been extracted for accurate modeling of the structure in SPICE tools. Furthermore, all the obtained parameters which are related to AC operation show excellent performance of the UR-SOI device. Comparison of the UR-SOI structure with a conventional-SOI (C-SOI) is done with a two-dimensional and two-carrier simulator SILVACO and all the extracted results promise marvelous superiority of the UR-SOI to the C-SOI device.