Electrodeposition of Crystalline Si Using a Liquid Ga Electrode in Molten KF–KCl–K2SiF6

Abstract

In this study, the electrodeposition of silicon (Si) using a liquid gallium (Ga) electrode in molten KF–KCl was further investigated. Electrochemical measurements and electrolysis were conducted at 923 K in a KF–KCl–K2SiF6 melt. Cyclic voltammograms at liquid Ga electrodes revealed that the reduction current at 0.6–0.9 V vs K+/K was due to the formation of Si–Ga liquid alloys. Si was deposited via potentiostatic electrolysis at 0.80 V using liquid Ga held in a crucible as an electrode. The Si grains were primarily located at the boundary of the Ga and the crucible, indicating that they were deposited from the Si–Ga liquid alloy. X-ray diffraction confirmed the crystallinity of the deposited Si, with a maximum grain size of approximately 6 mm. Potentiostatic electrolysis at varying charges showed that the Si grain size increased with increased charge, confirming the growth of crystalline Si. The Si grains obtained using the liquid Ga electrode were larger than those obtained using a liquid Zn electrode. Finally, the differences in Si crystal growth rates between the Ga and Zn electrodes were discussed.