Spectromicroscopy Studies of Silicon Nanowires Array Covered by Tin Oxide Layers

Abstract

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...

Nanostructured Silicon Matrix for Materials Engineering

“…As a result, the electronic density of states of the Sn atoms was reconstructed in the same direction, as discussed in our previous publication. [ 32 ] In summary, in the observed O K‐edge XANES spectra of all three surfaces under investigation, it is clear that the characteristic peak located at 531 eV was suppressed from the upper to the lower region in the deposit on the nanostructured surface in comparison to the planar surface, suggesting that less oxygen was present as SnO 2 on the surface, further confirming that the state distribution of tin along the SiNWs changed from SnO 2 to SnO and to metallic Sn from top to bottom along the SiNWs.…”

Tin/Tin Oxide Nanostructures: Formation, Application, and Atomic and Electronic Structure Peculiarities

“…However, the typical analytical characterization techniques in the lab, such as microscopy, spectroscopy, and diffraction, are mostly bulk methods which are not surfacesensitive and cannot detect the chemical/physical properties on the surface. In comparison to the lab techniques (where only X-ray photoelectron spectroscopy (XPS) is possible), synchrotron radiation facilities have a higher photon number, which leads to higher resolution and sensitivity to small material amounts (especially important for nano-scaled materials) and higher sensitivity, especially in the case of tin, which has a low photoionization cross-section, as shown in our previous publication [190]. The X-ray absorption near-edge structure (XANES) method has a probing depth of 5 nm compared to the probing depth of 2 nm for the XPS method.…”

“…Photo-emission electron microscopy (PEEM) in soft XANES spectroscopy mode can be efficiently applied for Sn-O system studies in different environments [220]. Only Kolmakov et al on SnO 2 nanowires [221] and Turishchev et al on tin oxide-covered silicon nanowire arrays [190] presented PEEM results, showing a lack of studies on the surface of low-dimensional tin oxide nanostructures, which makes this topic extremely important.…”

“…changes in Sn-O systems localized around silicon nanowires or planar silicon sur Photo-emission electron microscopy (PEEM) in soft XANES spectroscopy mode c efficiently applied for Sn-O system studies in different environments [220]. Only K kov et al on SnO2 nanowires [221] and Turishchev et al on tin oxide-covered silicon owire arrays [190] presented PEEM results, showing a lack of studies on the surf low-dimensional tin oxide nanostructures, which makes this topic extremely impor In our previous studies, we showed the possibility of applying XANES (NEXAFS) to identify Sn crystal phases in silicon nanowire matrices [42,190]. This nondestructive surface-sensitive technique allows the precise detection of metallic Sn, Sn(II), and Sn(IV), which originates from the electronic features, as shown in Figure 12 In our previous studies, we showed the possibility of applying XANES (NEXAFS) to identify Sn crystal phases in silicon nanowire matrices [42,190].…”

Formation of Nanostructured Tin Oxide Film on Porous Silicon

“…One of the materials used for the formation of nanostructures is tin dioxide (a wide bandgap n-type semiconductor) used as active layers in multisensor microsystems, UV detection systems, electrodes of lithium-ion batteries, electrocatalysts, as well as in polymer solar cells [33][34][35]. Tin is highly conductive to electricity; therefore, it can be used in electronic or microelectronic devices, including sensors and semiconductor components.…”