Hot electrons cathodes in high speed three-terminal devices: do they really make a difference?

Using a two-dimensional self-consistent ensemble Monte Carlo method, the effectiveness of the abrupt heterojunction, planar doped barrier, and doped homojunction as hot electron cathodes in realistic high speed semiconductor device structures is investigated. Both unipolar (vertical FET) and bipolar (heterojunction bipolar transistor) structures are examined, and results of device parameter optimization are given. Steady-state and transient device characteristics are compared, and low temperature (77 K) results are given. It is found that, when properly designed, hot electron cathodes can significantly improve device performance, especially at low temperatures. This potential has not always been realized in fabricated devices because of the complexity of the design