Abstract
Millimetre-wave transferred electron devices have been fabricated with a range of cathode contacts from a Schottky contact to an ohmic contact. DC measurements have shown that the degree of negative differential resistance and the ratio of forward and reverse bias threshold currents can be related directly to the state of the cathode contact. Corresponding rf measurements have shown similar trends in efficiency and `turn-on' performance, suggesting different modes of operation. A novel computer simulation has been developed to investigate these effects.