Transient simulation of AlGaAs/GaAs/AlGaAs and AlGaAs/InGaAs/AlGaAs hot-electron transistors

The intrinsic switching characteristics of tunneling hot electron transfer amplifier (THETA) devices has been simulated using a time-dependent ensemble Monte Carlo method. Results which show that there is no significant difference between the switch-on and switch-off times of THETA devices and that these switching times are always larger than the average total transit time through the base and the collector barrier are presented. The choice of the base width is important to determine the base transport factor, but it is not a direct measure of the intrinsic switching speed. The importance of velocity overshoot in the collector barrier region for ultra-high-speed device operation is demonstrated. An improved device structure that leads to subpicosecond switching speeds in the THETA structures is proposed.<
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