Ballistic electron transport across collector barriers in AlGaAs/GaAs hot-electron transistors

A Monte Carlo calculation has been performed to simulate the experiment of Heiblum and co-workers [Phys. Rev. Lett. 55, 2200 (1985)], regarding ballistic electron transport and the electron transit time across the AlGaAs collector barrier region in AlGaAs/GaAs tunneling hot-electron transfer amplifier devices. Ballistic transport is proven to be highly probable across a 1000-Å-thick collector barrier under retarding field and hot-electron injection conditions at 4.2 K. Applying accelerating fields in the barrier results in almost negligible ballistic fraction of the transmitted hot electrons because of electron scattering into the satellite valleys. This result seems paradoxical at first sight. However, it is typical for electronic transport in heterolayers and fully consistent with the interpretation of the experiments by Heiblum and co-workers. There exists a negative collector-base bias range which minimizes the collector barrier transit time, corresponding to the condition of large ballistic probability and simultaneously relatively little deceleration of the electrons by the applied retarding field.