Germanane is a single-layer crystal composed of
germanium with one
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...
bonded in the z-direction for each atom, in contrast to
germanene which contains no hydrogen. In
material science, great interest is shown in related single layered materials, such as
graphene
Graphene () is an allotrope of carbon consisting of a single layer of atoms arranged in a hexagonal lattice nanostructure. , composed of carbon, and silicene, composed of
silicon
Silicon is a chemical element with the symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic luster, and is a tetravalent metalloid and semiconductor. It is a member of group 14 in the periodic ta ...
. Such materials represent a new generation of semiconductors with potential applications in
computer chip
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...
s and
solar cells
A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon. . Germanane's structure is similar to
graphane
Graphane is a two-dimensional polymer of carbon and hydrogen with the formula unit (CH)n where ''n'' is large. Partial hydrogenation results in hydrogenated graphene, which was reported by Elias et al in 2009 by a TEM study to be "direct evidence ...
, and therefore
graphene
Graphene () is an allotrope of carbon consisting of a single layer of atoms arranged in a hexagonal lattice nanostructure. . Bulk germanium does not adopt this structure. Germanane has been produced in a two-step route starting with
calcium germanide. From this material, the calcium is removed by de-intercalation with HCl to give a layered solid with the empirical formula GeH.
[ The Ca sites in ]Zintl phase
In chemistry, a Zintl phase is a product of a reaction between a group 1 (alkali metal) or group 2 ( alkaline earth metal) and main group metal or metalloid (from groups 13, 14, 15, or 16). It is characterized by intermediate metallic/ ionic bond ...
CaGe2 interchange with the H atoms in the HCl solution, which leaves GeH and CaCl2.
Properties
Germanane's electron mobility is predicted to be more than ten times that of silicon and five times more than conventional germanium. Hydrogen-doped germanane is chemically and physically stable when exposed to air and water.direct band gap
In semiconductor physics, the band gap of a semiconductor can be of two basic types, a direct band gap or an indirect band gap. The minimal-energy state in the conduction band and the maximal-energy state in the valence band are each characteriz ...
,” easily absorbing and emitting light, and potentially useful for optoelectronics
Optoelectronics (or optronics) is the study and application of electronic devices and systems that find, detect and control light, usually considered a sub-field of photonics. In this context, ''light'' often includes invisible forms of radiat ...
. (Conventional silicon and germanium have indirect band gaps, reducing light absorption or emission.) In addition, the Ge atoms have higher spin-orbit coupling (as compared to C in graphene/graphane) which can allow us to explore the quantum spin Hall effect.
Electrical and Optical Properties
Researchers at the University of Groningen in the Netherlands and the University of Ioannina in Greece, have reported on the first field effect transistor fabricated with germanane, highlighting its promising electronic and optoelectronic properties.
References
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External links
Strong excitons in novel two-dimensional crystals: Silicane and germanane
Semiconductor fabrication materials
Germanium compounds
Optoelectronics
Solar cells
Two-dimensional nanomaterials
Metal hydrides