High performance Ni-Pd/GaAs Schottky barrier mixer diodes made by electroplating

Electroplating Ni-Pd binary alloy on GaAs, high cutoff and high reliability Schottky barrier mixer diodes for SHF reciever systems have been developed. This electroplating technique enables to form Schottky barrier without stray capacitance due to overlay and without increase of series resistance due to oxidation and contamination of the GaAs surface and thereby to realize high cutoff frequency more than 2000 GHz (DC). The Ni-Pd/GaAs Schottky barrier is also very stable. For instance MITF of 7.5 × 10⁷hours has been deduced at 60°C, which is three orders of magnitude longer than the conventional Ni/GaAs Schottky barrier´s. Using this mixer diode in a SHF downconverter, conversion loss as low as 2.9 dB and system noise figure as low as 4.3 dB have been obtained with a 200 MHz width at 12 GHz.