Germanane is a one-atom-thick sheet of hydrogenated puckered germanium atoms structurally similar to graphane.
Graphene has brought to the world’s attention the exceptional properties of two-dimensional (2D) materials. However, graphene’s lack of an intrinsic band gap and limited amenability to chemical modification has resulted in increasing interest in other 2D layered nanomaterials. Germanane is a one-atom-thick sheet of hydrogenated puckered germanium atoms structurally similar to graphane. It is a 2D nanomaterial generated via mechanical exfoliation from GeH.
Monolayer 2D materials such as germanane, hexagonal boron nitride (h-BN), silicene, silicane, molybdenum disulfide have attracted enormous interest for their potential applications in batteries, solar cells, optoelectronics, sensors, catalysts, composites and thermoelectrics. Most significantly, these materials will potentially meet the future requirements for large-area, transparent and flexible electronics.
In May 2013, Bianco et al. reported a unique method for generation of stable, single-layered germanane. The researchers synthesized millimeter-scale crystals of a hydrogen-terminated germanium multilayered graphane analogue (germanane, GeH) from the topochemical deintercalation of CaGe2.1 Advantages of germanane include:
• a direct band gap of 1.53 eV and an electron mobility ca. five times higher than that of bulk Ge.
• the chemical surface can be modified to adjust the band gap, temperature dependent stability, or other properties of the material.
Figure 1: Schematic of germanane (credit: Goldberger et al.)
The main drawback to germanane is ermanane, is its behavior with increased temperature, which could render it ineffective for electronic materials that operate at high temperatures. This may mean that it requires cooling to be of use or can only be utilized in low power applications. 2
Another potential application drawback is cost as germanium is far less abundant than silicon and carbon, which could give materials like graphene the lead in terms of commercial viability in the next decade.
References:
1Bianco, E.; Butler, S.; Jiang, S.; Restrepo, O. D.; Windl, W.; Goldberger, J. E.;Stability and Exfoliation of Germanane: A Germanium Graphane Analogue. ACS Nano 2013, 7, DOI:10.1021/nn4009406.
2 The New Skinny in Two-Dimensional Nanomaterials, Kristie J. Koski and Yi Cui†, Department of Materials Science & Engineering, Stanford University, Stanford, California 94305, United States, and Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States, www.stanford.edu/group/cui_group/papers/Skinny_2013.pdf
