The relationship of gate length to RF characteristics of SiC-MESFETs - RF characteristics of short-channel SiC-MESFETs

摘要

We studied the RF characteristics of SiC-MESFETs with gate lengths from 0.3 to 1.5μm that were fabricated on the same epitaxial wafer. When the gate length was less than 1.0μm, the cutoff frequency f{sub}t and maximum oscillation frequency f{sub}(max) were less dependent on the gate length. The degradation of these RF characteristics was apparently caused by the short-channel effect. To uncover the mechanism underlying this, we investigated static electrical characteristics, such as the transconductance and pinch-off voltage, of short-channel SiC-MESFETs and found that the short-channel effect occurred when the aspect ratio of the gate length to channel thickness was 5 or less.