A numerical analysis of submicrometer InP-transferred electron devices

A numerical technique combining the Boltzmann transport equation and a cathode mobility model has been used to simulate the nonuniform field configurations and the static and dynamic transport behavior of submicrometer InP-transferred electron devices (TEDs). Significant interrelated controlling features for the 70-230-GHz operation of these devices have been analyzed. They determine the manifestation of the current instabilities in the following ways: (1) the length has a significant effect on the velocity-field characteristics for submicrometer TEDs, and thus on the oscillation threshold as well as the upper-frequency limit for transit-time oscillations; and (2) the cathode mobility (boundary condition), doping density, and bias acting together have a dominant effect on the threshold and cutoff of the current instability. The numerical results can be used to determine the optimum efficiency and frequency of actual devices