A gallium arsenide ballistic transistor?

The authors review the work done in 1985 at the IBM Thomas J. Watson Research Center on measuring the ballistic transport of electrons in a gallium arsenide heterostructure hot-electron transistor. The device is referred to as the tunneling hot-electron transfer amplifier (Theta). The way in which the transistor functions as its own spectrometer is explained. The experimental results obtained with Theta are summarized. It was found that when no voltage is applied across the base-collector heterojunction, essentially only ballistic electrons are collected. These account for about 40% of the total number of electrons injected from the emitter at low temperatures. As the voltage across the collector is increased positively, up to 75% of them are collected.