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Abstract

The formation of hydrogen overlayers on the Zn-terminated ZnO(0001) surface has been reexamined by angle-resolved photoemission spectroscopy (ARPES). While low-energy electron diffraction patterns display the same (1 × 1) symmetry for different surface preparations, the electronic structure feature close to the Fermi level shows the formation of electron pockets, compatible with hydrogen-induced metallic states. Using ARPES and density functional theory (DFT) calculations, we show that hydrogen adspecies can also lead to metallization of this zinc-oxide surface in a similar manner as observed previously on ZnO(10̅10) and O-terminated ZnO(000̅1). Importantly, our DFT calculations indicate that these electron pockets are formed by sp hybridized states and therefore the angular distribution of the emitted photoelectron is significantly suppressed at the normal emission.