Electronic states for InAs(111)A-(2×2)S surface studied by angle-resolved photoemission spectroscopy

Valence electronic states for an InAs(111)A-(2×2)S surface are investigated by using synchrotron radiation angle-resolved photoemission spectroscopy (SRARPES). Three bands at 1.0–1.2, 3.3, and 4.6–4.7 eV below the Fermi level are found outside the projection of bulk bands along the M̄–Γ̄–M̄′ and Γ̄–K̄–M̄ azimuths. A band at 2.8 eV below the Fermi level is found in the normal emission spectra for the (2×2)S surface. This band is located within the projection of bulk bands and independent of the momentum component normal to the surface, k⊥. The four bands are ascribed to surface states or surface resonances for the (2×2)S surface. The origin of the surface bands is discussed.