Scanning tunneling microscopy study of dysprosium,gadolinium disilicide nanostructure on silicon (001).

摘要

The epitaxial growth of rare earth (RE) silicides on the silicon (001) surface has received some recent interest after it was discovered that self-assembled silicide nanowires form in the initial stages of growth. In this dissertation, Dy and Gd are chosen as prototypical systems for the study of RE silicide growth on Si (001) using scanning tunneling microscopy and low energy electron diffraction, with an aim of optimizing nanowire growth.; When depositing Dy and Gd on the Si (001) surface, three types of nanostructures can be formed: 2D reconstructions, nanowires, and 3D islands. The growth behavior of all of these structures is a function of growth temperature, annealing duration, and metal coverage. Two types of 2D reconstructions (2x4 and 2x7) are found, and their close relationship is revealed. Dy and Gd disilicide nanowire growth is achieved on both normal Si (001) and vicinal Si (001) substrates. 3D silicide islands which grow in competition with the nanowires can be suppressed by manipulating growth conditions. A relationship between the grown nanostructures and the crystallographic structures of bulk RE disilicides is established.