High-field transport in GaAs transistors

Resonant tunneling is used to explore the dynamics of electron transport in the electric field of reverse-biased GaAs n-p-n heterojunction bipolar transistor collectors. Extreme velocity overshoot is observed in a fraction of a percent of electrons which are accelerated ballistically in the Γ valley to energies greater than 1.5 eV. In addition, we show that Γ–X valley transfer is the dominant scattering mechanism for high-energy Γ valley electrons.