Growth Of A Smooth Epitaxial Gamma-Fe Film On The Cu(110) Surface

Iron films, grown on Cu(110) surfaces, are very rough when prepared under normal growth conditions. When Fe is deposited at room temperature. Stranski-Krastanov growth is observed, i.e. three-dimensional (3D) islands form. Here it is shown that a smooth 5 ML thick Fe film calm be grown on the Cu(110) surface by depositing the film at low temperature (T < 125 K) and subsequently anneal the film to 240 K. Since the thermodynamically stable state of the film is the state where the film has a rough surface. as found after deposition at room temperature. the smooth surface obtained by annealing after low-temperature deposition has to be considered as metastable Long-time stability of the smooth film, i.e. for periods of several hours, wits found at 140 K and below. Keeping the film at a temperature of 240 K or above results in the formation of large 3D islands as evidenced by the formation of (111) facets. The mechanism on which the preparation of the smooth film is based is discussed in terms of a competition between smoothening of the outermost, surface layer and nucleation and growth of holes in time film which leads to the formation of 3D islands.