Low-coverage alkali-metal-induced surface structural changes in III-V semiconductors: Photoemission extended x-ray-absorption fine-structure study of the Na/InP(110) interface

The atomic geometries of Na/InP(110) interfaces have been studied by photoemission extended x-ray-absorption fine-structure experiments. At low ($\frac{1}{8}$ monolayer) sodium coverage for room-temperature metal deposition, adatom-induced structural change within the surface unit mesh (reconstruction) of the substrate is found, as previously demonstrated for alkali-metal-covered transition-metal surfaces, while the relaxation in the unit mesh of the InP(110) surface is removed. The reconstruction is a change in the in-plane P—In bond length within the surface unit mesh. In the very low alkali-metal coverage regime, these surface structural changes are likely to influence Fermi-level pinning reported for very low coverages of alkali metals on (110) faces of InP and some other important III-V semiconductors.