Ballistic hot-electron transistors

We present an overview of work at the IBM Thomas J. Watson Research Center on the tunneling hot-electron transfer amplifier (THETA) device—including its use as an amplifier and as a tool for investigating ballistic hot-electron transport. In the initial, vertically configured version of the device, a quasi-monoenergetic, variable-energy, hot-electron beam is generated (via tunneling) which traverses a thin GaAs region and is then collected and energy-analyzed. As the hot electrons traverse the device, they are used to probe scattering events, band nonparabolicity, size-quantization effects, and intervalley transfer. A recent, lateral version of the device has been used to demonstrate the existence of ballistic hot-electron transport in the plane of a two-dimensional electron gas, and the associated possibility of achieving high gain.