This paper presents a new way to realize a clear control in the phase distribution of functional materials by utilizing the characteristic structural and physical properties of silicon surfaces (planar and nanostructured) and expects a wide range of applications in different areas. Phase selective Sn/SnO/SnO2 deposits on planar and nanostructured silicon surfaces were achieved by metalorganic chemical vapor deposition (MOCVD) using a volatile organometallic tin (IV) tert-butoxide as a tin source [1]. The morphology and microstructure of the obtained layers were examined by electron microscopy and diffraction methods. The phase distribution of the tin-containing layers was investigated using surface destructive methods, such as backscatter electron diffraction in coupling with focused ion beam surface treatment. The electronic and atomic structure of the obtained functional interfaces, on the surface and in the depth of the porous matrix, was investigated by non-destructive surface sensitive X-ray absorption near edge spectroscopy and photoemission electron microscopy using synchrotron radiation [2]. Based on the obtained experimental and ab-initio calculated data, one of the reasons that the tin-based phases distribution along silicon nanowires can be attributed to the formation of a temperature gradient as a result of the significant thermal conductivity difference between SiNWs layer and bulk Si. Additionally, during the MOCVD process, intense interactions between precursor molecules and tin-precursor decomposition by-products (hydrogen, butene) in the channels (nanocapillary) between SiNWs can happen, as a consequence of the random thermal motion of molecules in the nanocapillary, which leads to the formation of reducing agents, resulting in effective reduction of tin-based compounds to a metallic tin state for molecules with the highest penetration depth in SiNW matrices. In contrast to deposits on nanostructured silicon surfaces, deposits on planar silicon surfaces show significant oxygen exchange between strongly electronegative silicon and tin. This effect leads to the formation of a silica layer with inclusions of tin-based quantum dots (3-4 nm). These effects can be extremely useful for further surface engineering and key-extending into new applications of 1D and 2D silicon surfaces covered with functional oxides as an anode with high electronic conductivity for high-performance lithium-ion batteries, optical glasses or as active surface for biophotonics.
[1] P. Liu, A. Schleusener, G. Zieger, A. Bochmann, M. A. van Spronsen, and V. Sivakov, Nanostructured Silicon Matrix for Materials Engineering, Small 2023, 202206318.
[2] S. Turishchev, A. Schleusener, O. Chuvenkova, E. Parinova, P. Liu, Maxim Manyakin, S. Kurganskii, and V. Sivakov, Spectromicroscopy Studies of Silicon Nanowires Array Covered by Tin Oxide Layers, Small 2023, 202206322.