Photoemission from a Superlattice and a Single Quantum Well

Abstract
We present the first experimental evidence of tunneling and transport of electrons from quantum states in a GaAs/GaAlAs superlattice or a quantum well to a GaAs surface activated to negative electron affinity. The photocurrent versus light excitation energy shows definite structures which appear exactly at the calculated energies of the allowed optical transitions between the quantized levels of the valence and conduction bands. The 300- and 30-K results for the superlattice are successfully compared to luminescence experiments, and could lead to the production of highly polarized electron beams.