68 research outputs found
Graphene-like quaternary compound SiBCN: a new wide direct band gap semiconductor predicted by a first-principles study
Due to the lack of two-dimensional silicon-based semiconductors and the fact
that most of the components and devices are generated on single-crystal silicon
or silicon-based substrates in modern industry, designing two-dimensional
silicon-based semiconductors is highly desired. With the combination of a swarm
structure search method and density functional theory in this work, a
quaternary compound SiBCN with graphene-like structure is found and displays a
wide direct band gap as expected. The band gap is of ~2.63 eV which is just
between ~2.20 and ~3.39 eV of the highlighted semiconductors SiC and GaN.
Notably, the further calculation reveals that SiBCN possesses high carrier
mobility with ~5.14x10^3 and ~13.07x10^3 cm^2V^-1s^-1 for electron and hole,
respectively. Furthermore, the ab initio molecular dynamics simulations also
show that the graphene-like structure of SiBCN can be well kept even at an
extremely high temperature of 2000 K. The present work tells that designing
ulticomponent silicides may be a practicable way to search for new
silicon-based low-dimensional semiconductors which can match well with the
previous Si-based substrates
Interlayer-spin-interaction-driven Sliding Ferroelectricity in a van der Waals Magnetic Heterobilayer
Sliding ferroelectricity is widely existed in van der Waals (vdW)
two-dimensional (2D) multilayers, exhibiting great potential on low-dissipation
non-volatile memories. However, in a vdW heterostructure, interlayer sliding
usually fails to reverse or distinctly change the electric polarization, which
makes the electrical control difficult in practice. Here we propose that in a
vdW magnetic system, the interlayer spin interaction could provide an extra
degree-of-freedom to remarkably tune the electric polarization. Combining
tight-binding model analysis and first-principles calculations, we show that in
the CrI3/MnSe2 and other vdW magnetic heterobilayers, the switching of the
interlayer magnetic order can greatly change, even reverse the off-plane
electronic polarization. Furthermore, interlayer sliding causes a non-volatile
switching of the magnetic order and, thus, reverses the electric polarization,
suggesting a non-volatile magnetoelectric coupling effect. These findings will
significantly advances the development of 2D ferroelectrics and multiferroics
for spintronic applications
Substrate-induced half-metallic property in epitaxial silicene
For most practical applications in electronic devices, two-dimensional
materials should be transferred onto semiconducting or insulating substrates,
since they are usually generated on metallic substrates. However, the transfer
often leads to wrinkles, damages, contaminations and so on which would destroy
the intrinsic properties of samples. Thus, generating two-dimensional materials
directly on nonmetallic substrates has been a desirable goal for a long time.
Here, via a swarm structure search method and density functional theory, we
employed an insulating N-terminated cubic boron nitride(111) surface as a
substrate for the generation of silicene. The result shows that the silicene
behaves as a ferromagnetic half-metal because of the strong interaction between
silicon and surface nitrogen atoms. The magnetic moments are mainly located on
surface nitrogen sites without bonding silicon atoms and the value is about
0.12 uB. In spin-up channel, it behaves as a direct band gap semiconductor with
a gap of around 1.35 eV, while it exhibits metallic characteristic in spin-down
channel, and the half-metallic band gap is about 0.11 eV. Besides, both the
magnetic and electronic properties are not sensitive to the external
compressive strain. This work maybe open a way for the utility of silicene in
spintronic field
Magnetism in Graphene Systems
Graphene has attracted a great interest in material science due to its novel
electronic structrues. Recently, magnetism discovered in graphene based systems
opens the possibility of their spintronics application. This paper provides a
comprehensive review on the magnetic behaviors and electronic structures of
graphene systems, including 2-dimensional graphene, 1-dimensional graphene
nanoribbons, and 0-dimensional graphene nanoclusters. Theoretical research
suggests that such metal-free magnetism mainly comes from the localized states
or edges states. By applying external electric field, or by chemical
modification, we can turn the zigzag nanoribbon systems to half metal, thus
obtain a perfect spin filter.Comment: accepted by NAN
Stabilizing intrinsic defects in SnO
TThe magnetism and electronic structure of Li-doped SnO are
investigated using first-principles LDA/LDA calculations. We find that Li
induces magnetism in SnO when doped at the Sn site but becomes
non-magnetic when doped at the O and interstitial sites. The calculated
formation energies show that Li prefers the Sn site as compared with the O
site, in agreement with previous experimental works. The interaction of Li with
native defects (Sn V and O V vacancies) is also
studied, and we find that Li not only behaves as a spin polarizer, but also a
vacancy stabilizer, i.e. Li significantly reduces the defect formation energies
of the native defects and helps the stabilization of magnetic oxygen vacancies.
The electronic densities of states reveals that these systems, where the Fermi
level touches the conduction (valence) band, are non-magnetic
(magnetic).cancies. The electronic densities of states reveal that those
systems, where the Fermi levels touch the conduction (valence) band, are
non-magnetic (magnetic).Comment: Phys. Rev. B (2013), Accepte
Atomically thin mononitrides SiN and GeN: new two-dimensional semiconducting materials
Low-dimensional Si-based semiconductors are unique materials that can both
match well with the Si-based electronics and satisfy the demand of
miniaturization in modern industry. Owing to the lack of such materials, many
researchers put their efforts into this field. In this work, employing a swarm
structure search method and density functional theory, we theoretically predict
two-dimensional atomically thin mononitrides SiN and GeN, both of which present
semiconducting nature. Furthermore study shows that SiN and GeN behave as
indirect band gap semiconductors with the gap of 1.75 and 1.20 eV,
respectively. The ab initio molecular dynamics calculation tells that both two
mononitrides can exist stably even at extremely high temperature of 2000 K.
Notably, electron mobilities are evaluated as 0.888x
and 0.413x for SiN and GeN, respectively. The present
work expands the family of low-dimensional Si-based semiconductors.Comment: arXiv admin note: text overlap with arXiv:1703.0389
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