Angle-resolved inverse photoemission of GaP(110)

We have measured angle-resolved inverse-photoemission spectra of GaP(110) along the Γ̄X̄ and Γ̄X̄́ symmetry direction. An unoccupied, surface-state band near the bottom of the conduction band exhibits a downward dispersion along Γ̄X̄ and appears to be quite flat along Γ̄X̄́. Its minimum energy is found at X̄ to be EF+0.9 eV. Combining this value with angle-resolved ultraviolet-photoemission results, we find a direct surface-state band gap of 3.4 eV, while optical data show a first surface-sensitive transition around 2.8 eV. © 1987 Elsevier Science Publishers B.V. (North-Holland Physics Publishing Division).