Abstract : Emphasis was placed on fabricating very high cutoff frequency diodes having breakdown voltages in excess of 6 v. Devices were fabricated using both melt-grown GaAs and epitaxial material. The results indicate that the highest cutoff frequencies were achieved using melt grown GaAs and that the best devices fabricated have cutoff frequencies values very close to the maximum theoretical value for the material used. Twentyfive samples were completed. (Author)