Design and fabrication of 0.25- mu m MESFETs with parallel and pi -gate structures

The design and fabrication of 0.25- mu m MESFETs with a channel length of 2.3 mu m is reported. A comparison of the effect of the FET geometry ( pi and parallel gate structures) on device performance is described. MESFETs were fabricated using a hybrid optical/e-beam lithography process on active layers grown by MBE. FETs show a transconductance of 260 mS/mm and a threshold voltage of -3.0 V. No short-channel effects were observed. From RF measurements, an f/sub max/ of 90-120 GHz was obtained. Excellent device yield across a 3-in wafer and wafer to wafer was achieved.<
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