Monolithic microwave GaAs mixer diodes

A monolithic planar beam leaded GaAs mixer diode has been produced by using proton bombardment and a self-aligned metalization technique. Shadow masking of both the proton bombardment beam and the Schottky barrier metalization is used to produce an extremely tight and reproducible device geometry requiring only routine photoresist alignment. Isothermal annealing data has shown that for times in excess of 10,000 hours at normal storage temperatures, the isolation achieved by proton bombardment is not adversely affected. Diodes with a series resistance under 3.0 ohms with a zero bias junction capacitance of 0.06 pF have been realized, giving a zero bias cutoff frequency of 850 GHz. Preliminary RF data on typical devices yield a noise figure of 5.8 dB and a conversion loss of 3.8 at 10.7 GHz.