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

Abstract

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 were studied by cyclic voltammetry, chronoamperometry, scanning electron microscopy, atomic force microscopy and Raman spectroscopy. The 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 decreasing concentration of aluminum ions in the melt or with increasing 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.

Keywords

• molten salts
• co-deposition
• kinetics
• 3d nucleation/growth.