Electrochemical Vapor Deposition of Semiconductors from Gas Phase with a Solid Membrane Cell

Abstract

We demonstrate the feasibility of semiconductor deposition via the electrochemical reduction of gaseous precursors by the use of an anhydrous proton-conducting membrane, the solid acid CsHSO4, at 165 °C. This membrane electrode assembly was operated within the oxidation of hydrogen on a porous Pt anode and the deposition of Si or Ge under bias at the cathode from chloride-based gaseous precursors; SiCl4 and GeCl4 in an Ar flow with a reduction potential over -1.0 V (vs RHE).

Electrochemical Reduction of Gaseous CO2 at Low-Intermediate Temperatures Using a Solid Acid Membrane Cell

“…The detailed test conditions are described in the experimental section. The conductivity was determined to be ~10 −2 S•cm −2 , which was consistent with the well-known value of CsH 2 PO 4 [25].…”

“…Cesium dihydrogen phosphate (CsH 2 PO 4 ), a representative of superprotonic solid acids, was selected for this approach, owing to its high proton conductivity in the solid state. Superprotonic solid acids (MH n XO 4 , M = Na, K, Cs, X = P, S, and Se) are known for their high solid-state anhydrous proton conductivities at temperatures above their superprotonic transition temperature [25,26]. For CsH 2 PO 4 , the superprotonic transition temperature is ~241 • C [27,28].…”

“…First, CsH 2 PO 4 was readily synthesized by a simple precipitation method, and its crystal structure was confirmed by X-ray diffraction (XRD) patterns (Figure S1, reference: JCPDS Card No. 76-1836) [25,31], and electrochemical impedance spectroscopy (EIS) was used to determine its proton conductivity (Figure 2A). The detailed test conditions are described in the experimental section.…”