Growth of ultra-thin Ga and Ga2O3 films on Ni(1 0 0)

The growth of ultra-thin films of Ga2O3 on Ni(1 0 0) was investigated in the temperature range of 300–800 K by using Auger electron spectroscopy, low energy electron diffraction (LEED) and scanning tunneling microscopy. In addition, the growth of Ga at 300 K was also studied. For the formation of Ga2O3, first at 300 K, a 15 Å thick Ga layer was deposited on the Ni(1 0 0) surface. Oxygen adsorption until saturation leads to the formation of a thin amorphous Ga oxide on the top of a metallic Ga interlayer. Annealing up to 700 K leads to the formation of a well-ordered thin film of γ′-Ga2O3 which is accompanied by a coalescence and ordering of the Ga2O3 islands. Large terraces are found which are separated by step heights of 2 Å. The LEED pattern shows a 12-fold ring structure, which originates from two domains with hexagonal structure, which are rotated by 90° with respect to each other. The lattice constant of the hexagonal unit cells is determined to be 2.8 Å.