Electrodeposition of Continuous Silicon Coatings from the KF-KCl-K₂SiF₆Melts

Abstract

The silicon electrodeposition from the KF-KCl-(10 mol%) K2SiF6 melt at 943–1103 K has been studied. The polycrystalline continuous single-phase silicon coatings (∼99.9 wt% Si) have been obtained on the graphite, glassy carbon, silver, and tungsten substrates. The Raman spectroscopic study of the Si/C and Si/Ag interfaces has proved an absence of the intermediate phases. Two phases (Si and Ni2Si) were formed during the silicon electrodeposition on nickel.

Liquid‐Tin‐Assisted Molten Salt Electrodeposition of Photoresponsive n‐Type Silicon Films

“…Moreover, owing to the low solubilities of LiF and NaF in water, it is difficult to remove the adhered salt from the electrodeposited silicon films. [23] Recently, a water soluble KCl-KF salt was employed to prepare a thick (more than 50 µm) silicon film or silicon coatings by electrodeposition, [24][25][26][27] yet no photoresponse has been demonstrated. Since the solubility of K 2 SiF 6 in KCl-KF at 650 °C is much higher than that of SiO 2 in CaCl 2 at 850 °C, in the present study the feasibility of preparing a thick (>10 µm) and dense silicon film with photoactivity on a sheet substrate in KCl-KF-K 2 SiF 6 bath was investigated and a successful formulation was discovered.…”

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

“…38 In general, this pattern is similar to the Raman spectrum of a continuous Si coating on C obtained in our earlier work. 17 The main differences are in the shift of the strong band from the typical value for bulk crystalline Si (519 cm -1 ) to 511 cm -1 and the expansion of its left flank towards the value typical for amorphous Si (480 cm -1 ). 39 The same was observed in the Raman spectra of the Al-doped Si films obtained by radio-frequency magnetron sputtering, which did not have a well-crystallized structure.…”

“…The strong first-order Raman peak with a maximum at 511 cm -1 and two second-order bands at 300 and 940-1000 cm -1 can be attributed to the silicon vibrations. 17,37 In the high-frequency range, the spectrum contains two characteristic peaks at about 1330 and 1580 cm -1 , which correspond to the main carbon bands. 38 In general, this pattern is similar to the Raman spectrum of a continuous Si coating on C obtained in our earlier work.…”

“…5-8. Electrodeposition from molten salts is a promising method for producing thin silicon films due to the simplicity of the process, low capital and operating costs. [9][10][11][12][13][14][15][16][17][18][19] In addition, high deposition rates of continuous silicon layers and the ability to control the structure and morphology of films are advantages of this technique.…”

“…In particular, the molten KF-KCl-K2SiF6 mixture is a good electrolyte for obtaining continuous Si films. 10,[14][15][16][17][18] Stability in silicon concentration, relatively low operating temperatures (from 923 K), solubility in water, and less aggressiveness in comparison with pure fluoride melts are important advantages of this electrolyte. Partial replacement of KF-KCl with potassium iodide contributes to an additional decrease in the aggressiveness of the melt and the liquidus temperature; in addition, a decrease in the electrical conductivity of melts with KI provides the formation of more compact deposits.…”