Band Gap Characters and Ferromagnetic/Antiferromagnetic Coupling in Group-IV Monolayers Tuned by Chemical Species and Hydrogen Adsorption Configurations

Abstract

One-side semihydrogenated monolayers of carbon, silicon, germanium, and their binary compounds with different configurations of hydrogen atoms are investigated by density functional theory. Among three considered configurations, zigzag, other than the most studied chair configuration, is energetically the most favorable structure of one-side semihydrogenation. Upon semihydrogenation, the semimetallic silicene, germanene, and SiGe become semiconductors, while the band gap in semiconducting SiC and GeC is reduced. Semihydrogenated silicene, germanene, SiGe, and GeC with chair configuration are found to be ferromagnetic semiconductors. For semihydrogenated SiC, it is ferromagnetic when all hydrogen atoms bond with silicon atoms, while an antiferromagnetic coupling is predicted when all hydrogen atoms bond with carbon atoms. The effect of interatomic distance between two neighboring magnetic atoms to the ferromagnetic or antiferromagnetic coupling is studied. For comparison, properties of one-side and both-side fully hydrogenated group-IV monolayers are also calculated. All fully hydrogenated group-IV monolayers are nonmagnetic semiconductors with band gaps larger than those of their semihydrogenated counterparts.Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-015-1040-y) contains supplementary material, which is available to authorized users.

Tuning Electronic Properties of the SiC-GeC Bilayer by External Electric Field: A First-Principles Study

“…The Monkhorst–Pack scheme was used to sample the Brillouin zone with a (5 × 5 × 1) k-mesh. The optimized lattice parameters of SiC and GeC monolayers are 3.09 and 3.23 Å, and the bond lengths of Si-C and Ge-C are 1.79 and 1.86 Å, respectively, which are consistent with other theoretical and experimental results (3.09 and 3.23 Å) [32,33]. The lattice mismatch is about 4.3% between SiC and GeC, which has little effect on the electronic properties of the SiC/GeC heterostructure [34,35].…”

Novel hybrid monolayers SixGeySn1−x−y: first principles study of structural, electronic, optical, and electron transport properties with NH3 sensing application

“…To confirm this claim, we calculated the lattice constants of the proposed hybrid monolayers using the reported lattice constants of hybrid monolayers of SiGe, SiSn and GeSn as 3.963 Å, 4.29 Å, and 4.35 Å, respectively. 33–36 So, employing Vegard's law the calculated values of the lattice constant of monolayer Ge 0.25 Sn 0.25 Si 0.50 , Si 0.25 Ge 0.25 Sn 0.50 , and Sn 0.25 Si 0.25 Ge 0.50 are 8.253 Å, 8.64 Å, and 8.313 Å, respectively, which are very close to the computed values of the lattice constants of the hybrid monolayers. If we closely observe the hybrid monolayers there is a slight compression in the Sn–Si and Sn–Ge bonds and slight tensile stress in the Ge–Si bonds.…”

Bonding, structure, and mechanical stability of 2D materials: the predictive power of the periodic table

“…Table 4 provides the cohesive energies and structural data of the planar group IV carbides SiC, [112][113][114][115][116][117] GeC, 115,[118][119][120] and SnC 115,121,122 and the buckled monolayers SiGe, 115,123,124,128 SnSi, 115,122,125,126 and SnGe. 115,122,125,126 The dependence of the cohesive energy on bond length of these binary compounds is displayed in Fig.…”