In this paper, the influence of the conditions of chemical and electrochemical nickel plating of nanostructured silicon and subsequent heat treatment on the phase composition of Si/Ni structures with advanced interface is studied. Nanostructured silicon formed by chemical and electrochemical etching was used for the formation of a developed interphase surface. The resulting Si/Ni samples were analyzed using scanning electron microscopy, energy dispersive X-ray analysis, and X-ray phase analysis. The experiments have revealed the differences in phase composition of the Si/Ni structures obtained by different methods, both before and after heat treatment.
In this work we provided a review of the study of MACE (metal-assisted chemical etching) of Si with Ag, Pt, Ni and Au films and clusters. Type and shape of the metal mask play an important role in determination of morphology of the nanostructured layer. It is possible to form both wide range of porous layer and nanowires array. The basic features of the MACE with various types and shape of the metal were revealed.
Study of new materials and composites based on porous silicon is of great interest for electronics and microelectronics industry. Functional characteristics of structured layers are closely associated with their morphology properties and treatment conditions correspondently. In this work a porous silicon layers formed by metal-assisted chemical etching (MACE) with the use of gas adsorption-desorption method, scanning electron microscopy (SEM) and fractal geometry have been examined. Specific surface area given by multi-point BET method was about of 7 m2/g and 13 m2/g for n-Si and p-Si specimens correspondently. Surface fractal dimension Ds was estimated for p-type mesoporous silicon from BET results using Neimark’s thermodynamic approach, the value is Ds=2.86. “Slit islands” Mandelbrot’s algorithm was applied for analysis of SEM images and calculations of surface fractal dimension Ds, computation gives Ds = 2.52 for n-Si sample and Ds = 2.84 for p-Si sample. The study testified the fractal nature of porous layers formed by MACE and exhibits correlation between different methods of fractal dimension estimation. The results can be applied for improvement of methods of structured solids characterization.
Atmosphere water influence in the nanostructured silicon (NSS) was investigated by IR-spectroscopy and electron work function measurement. Long-term non-reversible dynamics of IR-spectra was found as a result of 100% humidity influence on the nanostructured silicon. It was indicated that air humidity affects on the work function. Dynamics of the electron work function consists of reversible and non-reversible components. Reversible component appears as strong anti-correlation between work function and humidity. Work function change of NSS is about 0.4 eV while the humidity changes between 0% and 100%. Reversible component can be explained by physical sorption of water molecules on the surface. Non-reversible component manifests as long-term decreasing trend of work function in humid atmosphere. Transition curve during abruptly humidity changes alters its shape. Non-reversible component can be explained by chemisorption of water.
A copper sulfide and bismuth sulfide thin films were deposited on Si/Ti substrate by successive ionic layer adsorption and reaction method at room temperature, using cupric chloride, bismuth chloride, complexing Na2EDTA and sodium sulfide aqueous solutions as precursors. The surface morphology, structural and electrical properties of the as-deposited films were investigated by scanning electron and atomic force microscopy, energy dispersive X-ray analysis (EDS), and 2-point probe methods. The films were found to be amorphous, rough with thickness 30 nm and 20 nm for CuSx and BiSx, respectively. Average atomic percentage of Cu:S and Bi:S in the as-deposited films was calculated as 1:1.5 and 2.3:3. It was noted that films possess resistive switching behavior. Ionic conductivity of the CuSx film was found to be 25,8·10-3 Ohm-1·cm-1 . Ionic conductivity of the BiSx film was found to be 16·10-3 Ohm-1·cm-1. Set voltages UON defined by I-V curves were found to be in the range 0,75-0,8 V/cm for both films. Reset voltages UOFF were found to be in the range 0,6-0,7 V/cm for both films. Thus, formed films can be used as active layers for memory devices application.