A theory of shot noise in quantum wells and applications in resonant tunneling heterojunction bipolar transistors

Some semiclassical arguments are presented to show that the noise associated with the current through a resonant tunnel (RT) diode is reduced by the feedback through the modulation of the barriers by the space charge in the well, and at high frequencies by the reduction in the velocity spread. Theoretical calculations of shot noise are carried out on a double-barrier, one-well structure. The results show that the noise power is a function of the energy bandwidth of the transmitted electrons and that the noise may be significantly reduced by the quantum wells. These results can be applied to heterojunction bipolar transistors that contain a quantum well, and it is shown that these resonant tunneling heterojunction bipolar transistors (RTHBTs) should have a lower noise figure than homojunction transistors