Nonplanar power field-effect transistor (V-f.e.t.)

Abstract

A high-frequency power junction field-effect transistor with a nonplanar V-shaped channel fabricated by preferential etching of (100) silicon is described. The structure of the transistor is very simple; it requires only three photolithographic masking steps, and the result is a short-channel device with a high packing density. The theory of operation and the fabrication of this device are discussed, and the experimental characteristics of a 30-channel interdigitated structure having an effective channel length of 2.8μm, a channel width of 0.82cm and an active area of 0.1mm2 are presented. This transistor exhibits a low-frequency transconductance of 87mS, a cutoff frequency of 1.2GHz and a power-dissipation density of 21W/mm2 of chip area. The application of the transistor in a tuned power amplifier operating at 224 MHz is discussed.