Electrochemical Etching of Germanium in Ionic Liquids without the Use of Toxic and Corrosive Reagents. Issue 12 (15th October 2021)

• Record Type: Journal Article
• Authors: Kozmenkova, Anna Ya.; Farafonova, Sofia D.; Saverina, Evgeniya A.; Galushko, Alexey S.; Ananikov, Valentine P.; Egorov, Mikhail P.; Jouikov, Viatcheslav V.; Syroeshkin, Mikhail A.
• Is Part Of: ChemNanoMat. Volume 7:Issue 12(2021)
• Page Start: 1355
• Page End: 1360
• Publication Date: 2021-10-15
• Subjects: electrochemical etching -- environmental compatibility -- germanium -- ionic liquids -- porous materials; Nanochemistry -- Periodicals; Nanostructured materials -- Periodicals; Nanochemistry; Nanostructured materials; Periodicals; 541.2
• DOI: 10.1002/cnma.202100338
• Languages: English
• ISSNs: 2199-692X

Abstract

Abstract: For the first time, the possibility of obtaining porous germanium from both single‐crystal and polycrystalline starting materials using environmentally friendly (in contrast to the commonly used HF and HCl) imidazolium ionic liquids (IL) was shown. It was demonstrated that pore formation depended significantly on the viscosity of the IL, on the etching current density and etching time, and on defects and imperfections of the substrate surface. By varying these parameters, the rates of two competing processes – formation and growth of pores and electropolishing – could be adjusted, consequently allowing germanium with a various structured surface, including a porous surface. In particular, using a more viscous IL (for example, [BMIM][PF6 ] versus [BMIM][BF4 ]) made it possible to reduce the rate of dissolution of the germanium dioxide surface layer; as a result, the formation and growth of pores became a dominant process. At the same time, the dissolution rate of the already formed porous layer (electropolishing) increased with the etching current density and the number of defects and imperfections of the germanium surface. Abstract : Porous germanium is promising for energy storage, sensing, photovoltaics, etc. For its preparation, a method comprising electrochemical etching with an ionic liquids was proposed. It prevents the use of HF or HCl and is therefore environmentally friendly. Ready‐to‐use protocols were developed to obtain materials with pore diameters in the range of 30–225 nm.