SPIN POLARIZED ELECTRON SOURCE

摘要

Provided is a spin polarized electron source having high spin polarization degree and external quantum efficiency while providing flexibility in selecting the materials of a substrate, a buffer layer, and a distorted superlattice layer. The spin polarized electron source comprises a substrate, a buffer layer, and a distorted superlattice layer formed on the buffer layer. In the spin polarized electron source, an intermediate layer is interposed between the substrate and the buffer layer, the intermediate layer being made of a crystal having a lattice constant larger than the lattice constant of a crystal constituting the buffer layer. This causes cracks in the direction perpendicular to the substrate to occur in the buffer layer due to a tensile distortion, so that the buffer layer becomes mosaic-like. As a result, since a glide dislocation in an oblique direction is not introduced into the distorted superlattice layer grown on the buffer layer, the crystalline property of the distorted superlattice layer is improved. Consequently, the spin polarization degree of excited electrons and the external quantum efficiency of polarized electrons are improved.