MICROWAVE PERFORMANCE OF OPTICALLY FABRICATED T-GATE THIN-FILM SILICON-ON-SAPPHIRE BASED MOSFETS

Microwave characteristics of n and p-MOS transistors fabricated in thin film (50 and 100 nm) silicon-on-sapphire with T-gate lengths drawn at 0.5 and 0.7 mu m are reported, The observed f(max) was as high as 32 GHz for a n-MOS 0.7 mu m gate length device. Minimum noise figure values of 1.4, 1.8, and 2.1 dB at 2, 8, and 12 GHz respectively were obtained in a 100 nm thick n-channel device, N-channel device results were comparable in the 50 acid 100 nn films, For the p-channel FETs, the thinner, more highly stressed films gave significantly better results than the thicker p-channel films. At 2 GHz, p-FET noise figures as low as 1.7 dB were found, These results are, to the authors' knowledge, the lowest reported noise figures for either the p- or n-channel devices of any silicon based FET technology, Thinner films showed better voltage gain (g(m)/g(out)) than the thicker films.