Physical review. B, Solid state · 1971 · 310 citations · 16 references
Natural SciencesMaterials SciencePhysicsOpticsSemiconductor MaterialsSurface ScienceOptical Properties Of SemiconductorsOptical Properties Of SolidsSemiconductor PhysicsSemiconductor SurfacesSurface PhysicsSurface SpectroscopyOptical AbsorptionOptical Absorption SpectraOptical TransitionsPhotoelectric EffectSurface Electronic StructureSurface Optical PropertiesSurface Oxidation StatesSurface States
The optical absorption due to surface states on ultrahigh vacuum cleaved Ge and Si surfaces has been directly measured. Results show an absorption extending to energies lower than the edge, which disappears when the cleaved surfaces are oxidized. Possible optical transitions giving rise to this absorption are discussed. It is concluded that the dominant processes are transitions between two bands of surface states located in the gap. Combining the present results with photoelectric data, the energy position of the surface bands in Si is given.
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