Design and analysis of heterojunction bipolar transferred electron devices

The design of the heterojunction bipolar transferred electron device (HBTED) is considered. MOCVD-grown AlGaAs/GaAs HBTEDs were fabricated and 60 GHz operation was confirmed by on-wafer measurements. Analysis of the device operation is aided by the use of Monte Carlo device simulations, equivalent circuit model simulations and two-dimensional (2-D) drift-diffusion model simulations and the simulation results are compared with measurements on the fabricated HBTEDs and HBTED test structures. The effects of the external base-collector region and current spreading in the collector region are investigated and the latter is found to be of great importance. Our simulations show that having an appropriately graded collector doping profile can compensate the current spreading and this hypothesis is supported by measurement results. Conclusions are drawn regarding the design of practical HBTEDs for mm-wave oscillator applications.