SYMMETRICAL AND ASYMMETRIC INGAP INGAAS/GAAS HETEROSTRUCTURE MESFETS AND THEIR APPLICATION TO V-BAND AMPLIFIERS/

Self-aligned T-shaped Au/WSiN gate i-InGaP/n-InGaAs/i-GaAs heterostruc ture MESFET's with a BP-LDD structure were developed for application t o microwave and millimeter-wave communication systems. Owing to the us e of tilted-angle n(+)-ion-implantation. symmetric and asymmetric stru ctures FET's can be fabricated on the same chip and low noise, high br eakdown voltage, and high power gain can be attained simultaneously. T he fabricated symmetric FET's, with a gate length of 0.13 mu m, exhibi t a current cutoff frequency of more than 70 GHz and a minimum noise f igure as low as 1.0 dB at 20 GHz, while the gate-drain breakdown volta ge is more than 8 V and the MSG is as high as 7.5 dB at 60 GHz in the asymmetric FET's on the same chip. V-band MMIC amplifiers fabricated u sing symmetric FET's exhibit a gain of more than 9 dB and a noise figu re of 6 dB over the 50 to 60 GHz frequency range.