Surface morphology of three-dimensional Si islands on Si(0 0 1) surfaces

Silicon deposition on ultrathin Si oxide films was used for growing three-dimensional (3D) Si islands on Si(0 0 1) substrates. While it was previously demonstrated that at growth temperatures from 450 to 570 °C hemispherical Si islands form which grow epitaxially with respect to the Si(0 0 1) substrate, we show that these islands exhibit an irregular surface structure. Our LEED data also reveal that pyramidal Si islands, appearing at growth temperatures between 570 and 680 °C, have {1 1 3} facets with a 3 × 1 reconstruction on the sidewalls. With increasing growth temperature, the decomposition rate of the Si oxide film gradually increases and the film completely disappears at T∼640 °C, whereas the pyramidal islands are observed at the growth temperatures up to 680 °C. This result indicates that the local minimum of the Si surface energy at {1 1 3} orientation supports the growth of pyramids on Si(0 0 1) surfaces under the flux of Si atoms even after complete decomposition of the Si oxide film.