Growth and electronic structure of Cu on Cr₂O₃(0001)

The deposition of Cu at room temperature on a Cr₂O₃(0001) substrate is studied by x-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy and low-energy-electron diffraction. The results indicate that at RT Cu is highly dispersed on the substrate at initial deposition. X-ray induced Auger spectra, Auger parameter and ultraviolet photoelectron spectroscopy show that at the initial coverage the deposited Cu is in the Cu(I) state due to the interaction of Cu with the Cr₂O₃ substrate; Cu becomes metallic at Cu coverages of >4 monolayer equivalent. The formation of Cu two-dimensional or quasi-2D patches is followed by the formation of Cu three-dimensional clusters. Cu grows epitaxially on the Cr₂O₃(0001) films as Cu(111)R30° as observed by low-energy-electron diffraction.