Exfoliation and Stability Studies of Germanane and its Derivatives
The Ohio State University
The discovery of graphene has demonstrated that stable single-layer sheets can be isolated from the bulk materials. In the previous work, we have successfully isolated single-layer hydrogen-terminated-germanium (germanane, GeH) sheets which have unique electronic properties distinct from the bulk materials. In order to understand the doping effect of GeH, we have synthesized phosphorus-doped germanane (P-GeH), gallium-doped germanane (Ga-GeH) and arsenic-doped germanane (As-GeH) via the topochemical deintercalation of CaGeP, CaGeGa and CaGeAs, respectively. Similar to GeH, the doped GeH crystals can also be exfoliated into single- and few-layer sheets on SiO2/Si substrates mechanically. The optimized tape for exfoliating GeH crystals into measurable multilayer flakes is polydimethylsiloxane (PDMS). Lithium phenylacetylide can be used to clean PDMS residues left on the flakes. All the four van der Waals materials can be oxidized in the air at different oxidizing rates but the oxidization is limited to the surface layers based on the X-ray photoelectron spectroscopy (XPS) data and atomic force microscopy (AFM) images. In addition, the oxidized layers are dissolvable in the HCl aqueous solution while the fresh layers are still resistant to the HCl aqueous solution.
Germanane, Doping effect, Mechanical exfoliation, Air stability