Structural and Electronic Properties of p(2×2) Phosphorus Layer on Au(100)

We present the superstructure formed during phosphorus deposition on the reconstructed Au(100)-hexagonal surface together with its electronic properties. Scanning tunneling microscopy and spectroscopy combined with X-ray diffraction are compared to first-principles calculations. All these results consistently indicate a p(2×2) phosphorus structure with P atoms in hollow sites above a strained Au(100) surface. At intermediate coverage, Au(100)-hexagonal domains coexist with the p(2×2) superstructure. For full coverage, the reconstruction is completely lifted. Structure factors deduced from theoretical calculations and those measured by diffraction are in excellent agreement and demonstrate that P atoms induce significant Au strain which promotes a 0.2 Å outward relaxation associated with the quadrimerization of the underlying Au atoms. From the point of view of an electronic density perspective, a peak at 3.6 eV is observed in the unoccupied states, which is also supported by density functional theory. This is explained by a transfer of electrons from the Au surface to the P atoms.