An environment-friendly method of electrochemical etching of germanium has been developed at the Zelinsky Institute
Silicon and germanium nanomaterials are widely used in light emitting devices, power supplies, and fluorescent labels. Etching, including electrochemical etching, is an effective tool for obtaining nanostructured materials with various useful properties. The electrochemical etching consists of immersing a conductive material to be etched into an etching bath and connecting it as an anode to a power source. As a result of etching, there is a significant increase in the specific surface area of the conductive material. Unfortunately, almost all currently known electrochemical etching methods are based on the use of highly toxic and corrosive hydrofluoric and hydrochloric acids.
In the Laboratory of analogues of carbenes and other unstable molecules of the ZIOC the possibility of obtaining porous germanium using environment-friendly imidazolium ionic liquids has been demonstrated for the first time. The researchers have shown that pore formation is highly dependent on the viscosity of the ionic liquid used, the current density, and etching time, as well as on defects and imperfections of the substrate surface. By changing these parameters, it is possible to regulate the rates of two competing processes - the formation and growth of pores and electropolishing, which leads to the production of germanium with a different surface structure. Separately, it should be noted that the developed approach can find application in many laboratories, since it involves the use of the simple undivided two-electrode cell in the galvanostatic mode.
Anna Ya. Kozmenkova, Sofia D. Farafonova, Evgeniya A. Saverina, Alexey S. Galushko, Valentine P. Ananikov, Mikhail P. Egorov, Viatcheslav V. Jouikov, Mikhail A. Syroeshkin Electrochemical Etching of Germanium in Ionic Liquids without the Use of Toxic and Corrosive Reagents ChemNanoMat 2021, accepted manuscript. DOI: 10.1002/cnma.202100338.