RF Characteristics of Short-Channel SiC MESFETs

摘要

Silicon carbide (SiC) MESFETs-with gate lengths from 0.3 μm to 1.5 μm-were fabricated on a semi-insulating substrate, and their RF characteristics were measured. These measurements showed that when the gate length is less than 1.0 μm, the cutoff frequency f_t and maximum oscillation frequency f_(max) of the SiC-MESFETs is less dependent on gate length. It was also found that the degradation of these RF characteristics is apparently caused by the short-channel effect. To uncover the mechanism underlying this finding, static electrical characteristics, such as the transconductance and threshold voltage of the fabricated short-channel SiC-MESFETs, were investigated; consequently, it was found that the short-channel effect occurred when the aspect ratio of gate length to channel thickness was five or less.