Electrodeposition of Crystalline Germanium on Glass

Abstract

The research objective of this work is to test the hypothesis that crystalline germanium can be deposited on insulating substrates through electrochemical-liquid phase epitaxy (ec-LPE). In doing so, this work establishes a new method of semiconductor-on-insulator fabrication. Semiconductor-on-insulator device constructs are at the heart of all modern electronics. Methods that simplify fabrication by lowering the thermal budget and eliminating hazardous precursors are highly desirable. Recently, a new method for the direct preparation of covalent semiconductor crystals at ambient conditions, ec-LPE, was demonstrated by our group. This method utilizes thin liquid metal films simultaneously to perform electrochemical reduction of precursors and to direct heterogeneous nucleation at an underlying substrate of interest. In this work, the fabrication of germanium-on-glass using ec-LPE is demonstrated for the first time. Amperometry, microscopy, and Raman spectroscopy will be presented to demonstrate the proof of principle, i.e. the growth of Ge crystals electrochemically on insulating glass. The surface chemistry of glass substrates will be discussed, including glass functionalized with (3-Aminopropyl)triethoxysilane (APTES), and N-(Trimethoxysilylpropyl)ethylene-diamine triacetic acid (EDTA–TMS). Surfaces with a higher chelating group density improved the efficacy of Ge ec-LPE. These results set the groundwork for semiconductor-on-insulator process development based on ec-LPE.