Improved MODFET performance through ion implantation in the gate region

Al
x
Ga
1-x
As/GaAs modulation-doped FET's (MODFET's) are reported which utilize for the first time a shallow low-dose p-type implantation under the gate region to improve the source-drain breakdown voltage, and the gate-channel forward turn-on and reverse breakdown voltages. Extremely low output conductances of less than 0.2 mS/mm are also obtained and the open-circuit dc voltage gains g
m
/g
d
exceed 250. Such improvements are important for achieving high RF power in microwave device applications, and have similarly significant implications for digital circuitry.