Exfoliation and Air Stability of Germanane
OHIO STATE UNIV COLUMBUS COLUMBUS United States
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Exfoliation of graphene has shown that it is not only possible to create stable, single atom-thick sheets from a crystalline solid, but that these materials have fundamentally different properties than the parent material. Modifying the surface of graphene has been challenging because of its sp2 hybridization. Within the same family of carbon there are the possibilities of layered materials that are structurally similar to graphene, however, contains the sp3 hybridization needed for functionalization. This functionalization could lead to a tunable band gap necessary for optoelectronics. Germanane, an sp3 derivative of graphene, can be mechanically exfoliated as single and few layers onto SiO2Si substrates. Exfoliation was achieved by mechanical exfoliation using molds of PDMS. Detection of the few and single layers were achieved via optical microscopy on 100 nm thick SiO2Si substrates. To obtain an accurate height profile for the sheets, atomic force microscopy AFM was used after calibration of the tip to samplesubstrate interaction. For use in optoelectronic and sensing applications, air stability of germanane must be probed. Attenuated total reflection Fourier transform infrared ATR-FTIR spectroscopy was used to detect changes at the germanane surface by monitoring the GeH stretching mode. There was no change observed over 60 days meaning that the germanane surface remains intact. Another technique used to probe the surface was X-ray Photoelectron Spectroscopy XPS. XPS spectra showed that the surface layer slowly oxidizes in air over the span of 5 months, while the underlying layers are resilient to oxidation based on etching 0.5 nm of surface.
- Physical Chemistry
- Atomic and Molecular Physics and Spectroscopy