ELECTROLUMINESCENCE SPECTROSCOPY IN A HIGH MAGNETIC-FIELD OF THE BALLISTIC-ELECTRON ENERGY-DISTRIBUTION IN SINGLE-BARRIER HETEROSTRUCTURES

A high-resolution electroluminescence study of the hot-electron energy distribution, and of the nature of the tunneling processes, in GaAs/AlxGa1-xAs single-barrier p-i-n diodes is reported. Application of quantizing magnetic fields permits electron injection from narrow, well-defined electron states into the collector region, even at high emitter density. As a result ballistic-electron peaks, accompanied by their LO-phonon cascade, are clearly resolved. Cross-barrier recombination is also observed. The energy distribution of the ballistic electrons is shown to reflect exactly that of the emitter electrons, even though the density is 105 times lower, thus demonstrating that the two-dimensional to three-dimensional tunneling process is elastic and independent of the in-plane motion. The energy relaxation of the ballistic electrons is shown to be dominated by LO-phonon emission, with energy randomization by, e.g., carrier-carrier scattering playing no significant role. © 1995 The American Physical Society.