Photoemission and LEED characterization of Ni2P(0 0 0 1)

Ion bombardment of Ni2P(0 0 0 1) produces a disordered, Ni-rich surface. For annealing temperatures above 450 K, long range ordering occurs, and the surface Ni/P ratio decreases. Annealing above 700 K produces an ordered (1 × 1) hexagonal surface with a composition near that expected for a simple stoichiometric termination of the bulk structure. Variations in photoemission spectra are observed along with the changes in composition associated with the long range ordering of the surface. UPS spectra change from Ni metal like to Ni2P like, with a corresponding decrease in the density of states at the Fermi level. The splitting between the Ni 2p3/2 main and satellite peaks increases as the Ni/P ratio increases, likely due to poorer screening of the photoemission final state as a result of the decreased density of states at the Fermi level.