Si Electrochemical Liquid Phase Epitaxy: Low-Temperature Growth of Hyperdoped Epitaxial Si Films

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.