High-speed logic at 300K with self-aligned submicrometer-gate GaAs MESFET's

The fastest room-temperature logic gate operation yet reported has been achieved with an improved technology for self-aligned ion-implanted GaAs MESFET's. The procedure involves fabrication of 0.75/0.6-µm "T-gate" structures using electron-beam lithography, and employs arsenic-overpressure capless annealing of the self-aligned n+-implant. Minimum propagation delays of 15.4 ps/ stage were obtained for several of the ring oscillators, and none of the oscillators fabricated showed propagation delays longer than 17.0 ps. The fabrication technology and experimental results are described.