A silicon-on-insulator metal–semiconductor field-effect transistor with an L-shaped buried oxide for high output-power density

Abstract

We describe a novel silicon-on-insulator metal–semiconductor field-effect transistor with an L-shaped buried oxide (LB-SOI MESFET) and its maximum output power density (Pmax). To optimize the surface electric field and improve the breakdown voltage, we eliminated part of the oxide and replaced it with n-type silicon. By creating an n+–n region on the source side and modifying the electric field distribution, the breakdown voltage improved by 42% compared to a conventional device. Channel control is realized by varying the depletion layer width underneath the metal gate contact. This modulates the thickness of the conducting channel and thus controls the current between the source and the drain. Continuation of the n-type silicon on top of the buried oxide after the gate metal changes the depletion layer and increases the total channel charge for conduction, so the drain current increases by a factor of five compared to a conventional SOI MESFET. In addition, Pmax is increased by a factor of 17.7 with respect to a conventional structure, which is important for large-signal analog applications. Consequently, our novel LB-SOI MESFET has superior electrical characteristics.