Si Electrochemical Liquid Phase Epitaxy: Low-Temperature Growth of Hyperdoped Epitaxial Si Films
Nathanael Downes, Joshua DeMuth, Jacob Waelder, Quintin Cheek, Hannah Bartels, Stephen Maldonado
Abstract
Epitaxial films of Si have been prepared at room temperature by electrochemical liquid phase epitaxy (ec-LPE). Crystalline Si films were grown on both Si(111) and Si(100) substrates, demonstrating clear evidence of low-temperature homoepitaxy. The ec-LPE method was demonstrated as a hybrid approach that combined elements of conventional electrodeposition and traditional liquid phase epitaxy. Voltammetric and amperometric data were collected that indicated conditions where Si ec-LPE is possible with SiCl4 in propylene carbonate electrolyte and eutectic gallium indium (e-GaIn) thin-film electrodes. Scanning electron micrographs, scanning transmission electron micrographs, and electron and X-ray diffraction data demonstrated that epitaxy extended throughout films that were several microns in thickness. Raman spectra, high-resolution X-ray diffraction data, time-of-flight secondary ion mass spectrometry, and energy-dispersive elemental mapping indicated that the as-prepared films were uniformly hyperdoped with Ga at >10 at %. These cumulative results demonstrate a distinct new way to realize crystalline Si films suitable for optoelectronic applications.