Nucleation-Mediated Lateral Growth of Crystalline Islands on Foreign Substrate: an Origin of Long-Range Ordering in Pattern Formation

Abstract

Heteroepitaxial thin film growth may start by nucleating three‐dimensional (3D) or two‐dimensional (2D) islands on foreign substrate. Depending on the interfacial energies, heteroepitaxial growth can be categorized into three modes: Frank‐van der Merwe (FM), Stranski‐Krastanow (SK), and Volmer‐Weber (VW). In this lecture, we concentrate on the detail process of horizontal extension of a crystalline island on foreign substrate via successive nucleation at the concave corner of the crystal facet and the foreign substrate. It is demonstrated that due to the difference of surface tensions at the concave corner, once a nucleus appears at the corner, the crystallographic orientation of the nucleus is spontaneously twisted. By successive nucleation at the concave corner, the crystalline layer develops laterally, with its crystallographic orientation continuously rotated. Such a previously untouched effect could be the physical origin to form a few regular spatial patterns in the interfacial growth. A theory is developed, which provides a criterion to observe such an effect in the nucleation‐mediated lateral growth.