Correlating the Anisotropic Etching Behavior in Layered Chalcogenide Sb2Te3 with Crystal Defect Distribution

As the reverse process of crystal growth, the anisotropic etching is effective to tailor the morphology of two-dimensional materials, leading to the formation of a thermodynamically unfavored crystal shape. The etching behavior is usually related to the crystal defects. However, direct experimental evidence revealing the influence of the crystal defect distribution on preferential etching and anisotropic morphology evolution is still lacking. In this work, we observe that during vapor-solid synthesis of layered chalcogenide Sb2Te3, the regulation of growth temperature can induce the symmetry-dependent anisotropic etching behavior, and the morphology evolution from typical triangular to multibranched fractal structures occurs. By utilizing the complementary combination of infrared and electron microscopy, the multiscale inhomogeneity evolution from 3-fold symmetric crystal defect distribution to material density difference is recognized, to which the high-temperature-induced anisotropic etching behavior is directly related. Therefore, our findings provide valuable insights into the controlled synthesis of far-from-equilibrium-shaped nanocrystals in which the defect-related anisotropic etching dominates the morphology evolution.