Electroluminescence of ballistically injected electrons in AlGaAs/GaAs heterodiodes

We have observed hot-electron electroluminescence in AlGaAs/GaAs heterodiodes. The resolution provided by the luminescence technique allows ballistically launched electrons to be clearly distinguished from those that have emitted one or more longitudinal-optical phonons. The electroluminescence consists of a series of peaks spaced by one-LO-phonon energy whose width is in agreement with a calculation of the energy distribution of the injected electrons. The position of the ballistic peak provides a new way to accurately measure the conduction-band offset in semiconductor heterostructures.