Silicon overlayer growth on clean and hydrogen-terminated two-dimensional holmium silicide

The growth of silicon overlayers on both two-dimensional (2D) holmium silicide and hydrogen-terminated 2D holmium silicide grown on Si(111) has been investigated using scanning tunneling microscopy (STM). In the nonhydrogen-terminated case, the surface is heavily islanded, exhibiting the 7×7 and 2×1 silicon reconstructions. Growth on the hydrogen-terminated surface differs substantially, being better ordered and less heavily islanded. Growth mechanisms are proposed to explain these observed differences. STM data are also presented from the hydrogen-terminated 2D holmium silicide surface.