Revealing quantitative 3D chemical arrangement on Ge-Si nanostructuresRevealing quantitative 3D chemical arrangement on Ge-Si nanostructures
Faculty of Sciences. Physics
2009Washington, D.C., 2009
The journal of physical chemistry : C : nanomaterials and interfaces. - Washington, D.C., 2007, currens
113(2009):21, p. 9018-9022
University of Antwerp
The knowledge of composition and strain with atomic resolution is of utmost importance for the understanding of the chemical and electronic properties of alloyed nanostructures, and they can only be extracted in a self-consistent fashion. As an example, several works have addressed the issue of strain and chemical composition on self-assembled epitaxial islands using different techniques such as X-ray diffraction, scanning probe microscopy and transmission electron microscopy (TEM). However, limited information is available on the 3D chemical composition of such nanostructures. Here, we demonstrate the use of a quantitative high-resolution transmission electron microscopy (QHRTEM) technique to obtain two-dimensional (2D) projected chemical maps of epitaxially grown Ge−Si/Si(001) islands, with high spatial resolution, at different crystallographic orientations. Combining these data with iterative simulation, the reconstruction of the three-dimensional (3D) chemical arrangement on the strained Ge−Si/Si(001) islands was realized. This methodology can be applied for a large variety of strained crystalline systems, such as nanowires, epitaxial islands, quantum dots and wells, and partially relaxed heterostructures.