Electrodeposition of aluminum-doped thin silicon films from a KF-KCl-KI-K2SiF6-AlF3 melt

Abstract

Cyclic voltammetry, chronoamperometry, scanning electron microscopy, atomic force microscopy, and Raman spectroscopy were used to study the regularities of silicon and aluminum co-deposition on glassy carbon from KF-KCl (2:1) - 75 mol% KI - 0.15 mol% K2SiF6 - (up to 0.15 mol%) AlF3 melts at 998 K. Cyclic voltammograms demonstrated the presence of only one cathodic peak (or nucleation loop at a low reverse potential) and the corresponding anodic peak. The cathodic peak shifted in the cathodic direction with a decrease in the concentration of aluminum ions in the melt or an increase in the scan rate. The Scharifker - Hills model was used to analyze potentiostatic current density transients and estimate the values of the apparent diffusion coefficient and the number density of nuclei. The morphology and elemental analysis of the samples obtained during potentiostatic and galvanostatic deposition for 30-60 s were studied. Continuous thin silicon films doped with aluminum were obtained under galvanostatic conditions.

Silicon electrowinning by molten salts electrolysis

“…The authors confirm that SiC was not formed on graphite during the Si deposition, whereas the presence of SiC (thickness of 10 µm) intermetallics was reported by Bieber et al (2012). Adding KI to KF-KCl melt would reduce the melt's aggressiveness and liquidus temperature but decrease the electrical conductivity (Laptev et al, 2021). However, the reduced electrical conductivity would contribute to forming more compact and adhesive Si films (Laptev et al, 2020).…”

Silicon Electrodeposition for Microelectronics and Distributed Energy: A Mini-Review

“…The continuous appearance of new works devoted to the development of methods for producing silicon and silicon-based materials indicates the presence of shortcomings in the existing methods and the relevance of searching for new energy-efficient and resource-saving methods for producing silicon. In particular, these concerns relate to works aimed at the synthesis of silicon from iodide melts [38,39], organic electrolytes, and ionic liquids [16,17,40]. Table 1 shows the parameters and typical results of silicon electrodeposition from molten salts.…”

Electrodeposition of Silicon from the Low-Melting LiCl-KCl-CsCl-K2SiF6 Electrolytes

“…A glassy carbon crucible (6) with the studied electrolyte was placed at the bottom of a quartz cell (4), which was closed with a fluoroplastic lid with fittings (3). Thermocouple (1), glassy carbon working electrode (GC) (7), silicon counter electrode (9), and silicon quasi-reference electrode (QRE) (8) were attached to the fittings using rubber plugs (2).…”

“…1 However, for the effective work of the Si-based anode in LIB, silicon must be represented in the form of nano-and micro-sized fibers and ordered particles, [2][3][4] high-purity films, 5 as well as in the form of nano-sized particles with a controlled content of trace elements of group III or V of the periodic table of elements. 6 To obtain such silicon, methods of electrochemical synthesis from molten halide electrolytes with additives of silicon compounds (K 2 SiF 6 , SiO 2 , Na 2 SiF 6 , SiCl 4 , etc.) are promising.…”