Surface ordering of P-rich InP(001): Hydrogen stabilization vs electron correlation

The influence of hydrogen on the reconstruction of InP(001) surfaces is studied by first-principles calculations. One-monolayer phosphorus forming oppositely buckled dimers with one hydrogen adsorbed per dimer is energetically favored for a wide range of surface preparation conditions. The electronic structure and STM image calculated for this adsorbate geometry agree well with the experimental findings obtained after annealing of MOVPE-grown InP samples. The Si(001)-like surface ordering as well as the surface band gap of more than 1 eV, supposedly arising from electron correlation effects [Li et al., Phys. Rev. Lett. 82, 1879 (1999)], are naturally explained by the hydrogen-stabilized surface structure favored by the total-energy calculations.