China
Africa
Explore chapters and articles related to this topic
Psychopathology
Published in Richard Kerslake, Elizabeths Templeton, Lisanne Stock, Revision Guide for MRCPsych Paper A, 2018
It is an admitted fact that although 2D materials such as graphene, silicene, germanene, and stanene (the so-called xenes) are very prominent materials, all of them are virtually unusable in pristine forms. Apparently, the interesting properties of these 2D materials originate from defects or doping impurities that can create local resistivity (opening its band gap), enhancement of its free-carrier density, or appearance of anomalous magnetic properties. Chapter 10 studies the substitution of boron, carbon, and nitrogen on germanene. These three guest atoms have three, four, and five outermost electrons, so it is very suitable to have a complete understanding of the doping phenomenon of one of the xenes. Compared with other xenes, an important advantage of germanene is that it can be more easily functionalized so that synthesis can be more easily accomplished by chemical methods. Also for that reason, the physical and chemical properties of germanane can be easily adjusted, and it is expected to be used in the field of energy conversion and storage.
Effect of Al doping on the electronic structure and optical properties of germanene
Published in Molecular Physics, 2022
Jianlin He, Guili Liu, Lin Wei, Xinyue Li
In 2013, Elisabeth Bianco et al [52] synthesised germanane and fully-hydrogenated germanene (FHgermanene) for the first time in an experiment and found that germanane has a direct bandgap of 1.53 eV and electron mobility five times higher than that of overall germanium. Another possible hydrogenated germanene is unilateral semi-hydrogenated germanene (SHgermanene). Energy band structure calculations for SHgermanene revealed that it has a direct bandgap of 1.3 eV, which is in general agreement with the 1.32 eV obtained in the literature [31]. Wang et al [53] found that unilateral germanene hydrides produce localised and unpaired 4p electrons in unhydrogenated germanium atoms and introduce ferromagnetism into the germanene monolayer without doping, cutting, or etching. It has been shown that semi-hydrogenated and fully-hydrogenated have a greater effect on the electronic structure of germanene and that hydrogenated germanene is more stable [31]. However, the electronic structure of Al-doped germanene by semi-hydrogenation and full-hydrogenation has not been studied so far. Therefore, we chose the model with 25% doping concentration and the largest bandgap change for the semi-hydrogenated and fully-hydrogenated calculations to compare the changes in their properties before and after hydrogenation, as shown in Figure 7 (where green represents Ge, pink represents Al, and white represents H). According to the definition, the binding energies of Al-doped germanene in the three systems of unhydrogenated, semi-hydrogenated, and fully hydrogenated were calculated as −3.658 eV, −3.261 eV, and −3.263 eV, respectively. This may be due to the strong interaction of the double Al atoms with the surrounding H and Ge atoms, which deforms the structure and makes it less stable.