VALENCE-BAND STATES OF H-GAAS(110)

The two-dimensional surface electronic band structure of H:GaAs(110) i s studied by angular resolved ultraviolet photoemission spectroscopy a long the XBAR'-MBAR and XBAR-MBAR symmetry lines and in the high symme try points of the surface Brillouin zone. Three surface state bands ar e resolved in the first 5 eV below the upper valence band edge. A comp arison with theoretical band structure calculations yields a satisfact ory agreement, giving evidence of hydrogen induced GaAs(110) surface d erelaxation. The clean GaAs(110) surface electronic band structure is studied comparing results with available theoretical and experimental data.