To provide implement a spin-polarized
electron generating device having high
spin polarization and high external
quantum efficiency while allowing a certain degree of freedom in selecting materials of a substrate, a buffer layer, and a strained
superlattice layer.In a spin-polarized
electron generating device having a substrate, a buffer layer, and a strained
superlattice layer formed on the buffer layer, an intermediate layer formed of a
crystal having a
lattice constant greater than that of a
crystal used to form the buffer layer intervenes between the substrate and the buffer layer. With this arrangement,
tensile strain causes cracks to be formed in the buffer layer in a direction perpendicular to the substrate, whereby the buffer layer has mosaic-like appearance. As a result, glide dislocations in an oblique direction do not propagate to the strained
superlattice layer to be grown on the buffer layer, thereby improving
crystallinity of the strained superlattice layer. Accordingly,
spin polarization of excited electrons and external
quantum efficiency of polarized electrons improve.