Total-current-spectroscopy study of the electron states of clean and hydrogen-chemisorbed GaP(1̄1̄1̄)1 × 1 surfaces

Clean and hydrogen-chemisorbed GaP(1̄1̄1̄)1 × 1 surfaces have been studied using total current spectroscopy. Relative to the valence band maximum, one occupied surface state at −0.4 eV (or −1.2 eV) and one empty surface state at 1.1 eV are observed on the clean GaP(1̄1̄1̄)1 × 1 surface. Hydrogen atoms begin to adsorb on the clean surface at a low hydrogen exposure of 60 L (1 L = 10−6 Torr · s), A hydrogen-induced surface state at about − 7.0 eV relative to the valence band maximum on the hydrogen-adsorbed GaP(1̄1̄1̄) surface has been observed. A preliminary interpretation of these data is given.