Nonplanar power field-effect transistor /V-F.E.T./

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 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 2.8 micrometers, a channel width of 0.82 cm and an active area of 0.1 sq mm are presented. The transistor exhibits a low-frequency transconductance of 87 mS, a cutoff frequency of 1.2 GHz and a power-dissipation density of 21 W/sq mm of chip area. The application of the transistor in a tuned power amplifier operating at 224 MHz is discussed.