An atomic force microscopy study of thin copper oxide films grown by molecular beam epitaxy on MgO(100)

The formation of thin copper oxide (CuO) films on MgO(100) was studied by reflection high-energy electron diffraction (RHEED) and atomic force microscopy (AFM). The CuO films were grown by molecular beam epitaxy using NO2 as oxidant. For coverages exceeding 3 nm, the RHEED patterns indicate a two-dimensional growth of the CuO films with CuO(111) planes parallel to MgO(100). The in-plane epitaxial relationship is deduced as CuO[(1) over bar 10]parallel to MgO[011], The real space AFM images show that the CuO films exhibit a grain morphology with an average lateral dimension of the order of 200 nm. For CuO coverages above 5 nm, the secondary grains show a pronounced growth.