Surface characterization of self-assembled N-Cu nanostructures

► N2+ implantation and annealing of a Cu(0 0 1) surface. ► N diffuses to the surface and reacts to form c(2 × 2) Cu-N nanostructures. ► N atoms locates on the four-fold hollow site of the Cu(0 0 1) surface above it. ► DFT calculations estimate N height above the surface to be 0.25 Å. ► The appearance of a gap, consistent with the semiconductor character of Cu3N, is apparent in the N-Cu sample.