Chemical etching of a semiconductor surface assisted by single sheets of reduced graphene oxide

Catalyst-assisted chemical etching is an emerging technology for fabricating a variety of three-dimensional nanostructures on a semiconductor surface for future electronic and optical devices. In contrast to conventional wet etching using noble metals, we performed a fundamental study on the chemical etching of a Ge surface assisted by dispersed sheets of reduced graphene oxide (rGO) in water with dissolved O-2 molecules. We found that a monolayer sheet of rGO on Ge does not act as a mask but as a chemical tool that enhances etching under the entire sheet. This is probably caused by the dissociation of adsorbed O-2 molecules at the edges of vacancies in an rGO sheet, which leads to the formation of a soluble GeO2 layer. We also propose that the reagents and by-products involved in this etching diffuse along the interface between an rGO sheet and the wall of etched Ge, which we believe is a key for achieving higher etching rates. This study is expected to lead to a nanoscale manufacturing process for semiconductor surfaces free from noble-metal contamination. (C) 2017 Elsevier Ltd. All rights reserved.