Because of the large energy gap and very high electron mobility, gallium arsenide is theoretically the best suited semiconductor for the fabrication of high Q microwave diodes. Until recently, these properties could not be fully utilized for the fabrication of high voltage diodes suitable for harmonic generation and microwave switching because

structures with very thin ν regions could not be readily achieved. This paper describes epitaxial gallium arsenide diodes which combine high breakdown voltages with very low series resistances and permit full utilization of the inherent advantages of gallium arsenide. Breakdown voltages in excess of 200 volts were achieved with cutoff frequencies exceeding 100 kmc at -10 volts bias and power dissipations in the order of one watt. The electrical characteristics of these devices and details of their fabrication will be discussed.