Abstract
The reproducible epitaxial growth of 100 nm thick Ir (001) films was demonstrated on a heteroepitaxial stack consisting of 5 nm Ir and 100 nm yttria-stabilized zirconia (YSZ) grown on Si (001) substrates. It is shown that a 5 nm thick Ir layer grown by pulsed laser deposition in the same chamber as the YSZ film without breaking vacuum is the key to stabilizing Ir (001) epitaxial growth. Growth of the Ir seed layer with pure (001) orientation occurs only in a narrow growth temperature window from 550 to 750℃, and the fraction of Ir (111) increases at substrate temperatures outside of this window. The Ir seed layer prevents exposure of the YSZ film to air during sample transfer, and enables highly reproducible Ir (001) heteroepitaxy on YSZ buffered Si (001). In contrast, if Ir is grown directly on a bare YSZ layer, the films are prone to change orientation to (111). These results reveal that preserving the chemical and structural purity of the YSZ surface is imperative for achieving Ir (001) epitaxy. The mosaic spread values from 8 experiments are compared to show the high yield and reproducibility of the Ir (001) heteroeptiaxy by this approach. The improved Ir (001) epitaxial growth method is of great significance for integrating a variety of technologically important materials such as diamond, graphene, and functional oxides with the Si platform.
