Zn(Mn)O Surface Alloy Studied by Synchrotron Radiation Photoemission

The Mn/ZnO(0001) system was investigated by synchrotron radiation photoemission. The Mn/ZnO interface with 4 ML of manganese deposited onto the ZnO surface was annealed up to 500ºC. No Mn capping layer was found at the surface after annealing as was confirmed by scanning Auger spectroscopy experiment. We used a resonant photoemission to extract the Mn3d partial density of states in photoemission spectra. The Mn3d states contribute to the electronic structure of the system within 10 eV of the Fermi level. They show three features: a main peak at 3.8-4.5 eV, a valence structure at the top of the valence band (1-3 eV), and a broad satellite situated between 5.5 and 9 eV below E$\text{}_{F}$. The satellite/main branching ratio was determined to be 0.43, which is a fingerprint of strong hybridization between the Mn3d electrons and the valence band of the crystal. The hybridization effect in Zn$\text{}_{1-x}$ Mn$\text{}_{x}$O surface alloy is comparable to Zn$\text{}_{1-x}$Mn$\text{}_{x}$S and much higher than in Zn$\text{}_{1-x}$Mn$\text{}_{x}$Se, Zn$\text{}_{1-x}$Mn$\text{}_{x}$Te, and Ga$\text{}_{1-x}$Mn$\text{}_{x}$As semimagnetic compounds.