No abstract

Tin‐containing layers with different degrees of oxidation are uniformly distributed along the length of silicon nanowires formed by a top‐down method by applying metalorganic chemical vapor deposition. The electronic and atomic structure of the obtained layers is investigated by applying nondestructive surface‐sensitive X‐ray absorption near edge spectroscopy using synchrotron radiation. The results demonstrated, for the first time, a distribution effect of the tin‐containing phases in the nanostructured silicon matrix compared to the results obtained for planar structures at the same deposition temperatures. The amount and distribution of tin‐containing phases can be effectively varied and controlled by adjusting the geometric parameters (pore diameter and length) of the initial matrix of nanostructured silicon. Due to the occurrence of intense interactions between precursor molecules and decomposition by‐products in the nanocapillary, as a consequence of random thermal motion of molecules in the nanocapillary, which leads to additional kinetic energy and 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 the nanostructured silicon matrix. This effect will enable clear control of the phase distributions of functional materials in 3D matrices for a wide range of applications.

MAWCE) is a simple and low-cost approach to fabricate SiNWs with designable doping nature. In this technique, SiNWs are fabricated by nonuniform etching of silicon (Si) substrates, catalyzed by the electroless deposition of metal nanoparticles in aqueous acidic solutions. [4,5] This technique involves only wet chemical processing under near ambient conditions, leading to a low-cost operation. As a result, the electronic and optical properties of SiNWs can be engineered using the topdown and bottom-up techniques. [6,7] The obtained SiNWs exhibit unique optical properties, such as the scattering, absorption, transmission of light, and roomtemperature light emission. [8,9] Moreover, SiNW arrays with a high aspect ratio can be applied as matrices to deposit functional materials without additional material/surface contamination caused by a catalyst. Tin dioxide (SnO 2 ) is an essential functional metal oxide. SnO 2 thin films can be grown easily using different deposition techniques, such as spray pyrolysis, [10] sputtering, [11] laser ablation, [12] or chemical vapor deposition. [13] For specific applications, such as gas sensors, large specific surface areas are required to increase the sensor's performance. In this respect, low-dimensional nanostructures with the large specific surface areas can be used. In most cases, one-dimensional (1D) nanostructures, such as SnO 2 nanowires, can be controlled grown via a bottomup vapor-liquid-solid mechanism and MOCVD approach is one of the most promising 3D developed surface effective functionalization. [14][15][16][17] Despite its broad applications, weak fundamental studies on low-dimensional tin oxide nanostructures have been reported, particularly ones regarding the functionalization compatibility with other materials. This study reports the electronic structure specificity of low-dimensional SnO 2 nanostructures under common formation regimes and possible interatomic interactions under the phase composition formation, including measurements at the microscopic level. For extensively studying the composition and morphology of a sample's surface small areas at "one spot," spectromicroscopy techniques have been used. [18][19][20][21] For instance, the surface-sensitive soft X-ray absorption edge analysis has been conducted for studying the composite structure of Si-O [22][23][24][25] and Sn-O systems. [26][27][28][29] As the X-ray absorption fine structure is extremely sensitive to the The composition and atomic and electronic structure of a silicon nanowire (SiNW) array coated with tin oxide are studied at the spectromicroscopic level. SiNWs are covered from top to down with a wide bandgap tin oxide layer using a metal-organic chemical vapor deposition technique. Results obtained via scanning electron microscopy and X-ray diffraction showed that tin-oxide nanocrystals, 20 nm in size, form a continuous and highly developed surface with a complex phase composition responsible for the observed electronic structure transformation. The "one spot" combination, containing a chemic...