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 op eration is aided by the use of Monte Carlo device simulations, equivalent c ircuit model simulations and two-dimensional (2-D) drift-diffusion model si mulations and the simulation results are compared with measurements on the fabricated HBTEDs and HBTED test structures, The effects of the external ba se-collector region acid current spreading in the collector region are inve stigated and the latter is found to be of great importance. Our simulations show that having an appropriately graded collector doping profile can comp ensate the current spreading and this hypothesis is supported by measuremen t results. Conclusions are drawn regarding the design of practical HBTEDs f or mm-wave oscillator applications.