Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userOptical and electronic properties of two dimensional graphitic silicon carbide
198
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Optical and electronic properties of two dimensional few layers graphitic silicon carbide (GSiC), in particular monolayer and bilayer, are investigated by density functional theory and found different from that of graphene and silicene. Monolayer GSiC has direct bandgap while few layers exhibit indirect bandgap. The bandgap of monolayer GSiC can be tuned by an in-plane strain. Properties of bilayer GSiC are extremely sensitive to the interlayer distance. These predictions promise that monolayer GSiC could be a remarkable candidate for novel type of light-emitting diodes utilizing its unique optical properties distinct from graphene, silicene and few layers GSiC.
rate research
Read More
We discuss the fine structure and spin dynamics of spin-3/2 centers associated with silicon vacancies in silicon carbide. The centers have optically addressable spin states which makes them highly promising for quantum technologies. The fine structure of the spin centers turns out to be highly sensitive to mechanical pressure, external magnetic and electric fields, temperature variation, etc., which can be utilized for efficient room-temperature sensing, particularly by purely optical means or through the optically detected magnetic resonance. We discuss the experimental achievements in magnetometry and thermometry based on the spin state mixing at level anticrossings in an external magnetic field and the underlying microscopic mechanisms. We also discuss spin fluctuations in an ensemble of vacancies caused by interaction with environment.
A systematic review is made for the AA-, AB- and ABC-stacked graphites. The generalized tight-binding model, accompanied with the effective-mass approximation and the Kubo formula, is developed to investigate electronic and optical properties in the presence/absence of a uniform magnetic field. The unusual electronic properties cover the stacking-dependent Dirac-cone structures, the significant energy widths along the stacking direction, the Landau subbands (LSs) crossing the Fermi level, the $B_0$-dependent LS energy spectra with crossings and anti-crossings, and the monolayer- or bilayer-like Landau wavefunctions. There exist the configuration-created special structures in density of states and optical spectra. Three kinds of graphites quite differ from one another in the available inter-LS excitation channels, including the number, frequency, intensity and structures of absorption peaks. The dimensional crossover presents the main similarities and differences between graphites and graphenes; furthermore, the quantum confinement enriches the magnetic quantization phenomena in carbon nanotubes and graphene nanoribbons. The cooperative/competitive relations among the interlayer atomic interactions, dimensions and magnetic quantization are responsible for the diversified essential properties. Part of theoretical predictions are consistent with the experimental measurements.
We present a tight-binding (TB) model and $mathbf{kcdot p}$ theory for electrons in monolayer and few-layer InSe. The model is constructed from a basis of all $s$ and $p$ valence orbitals on both indium and selenium atoms, with tight-binding parameters obtained from fitting to independently computed density functional theory (DFT) band structures for mono- and bilayer InSe. For the valence and conduction band edges of few-layer InSe, which appear to be in the vicinity of the $Gamma$ point, we calculate the absorption coefficient for the principal optical transitions as a function of the number of layers, $N$. We find a strong dependence on $N$ of the principal optical transition energies, selection rules, and optical oscillation strengths, in agreement with recent observations cite{Bandurin2016}. Also, we find that the conduction band electrons are relatively light ($m propto 0.14-0.18 m_e$), in contrast to an almost flat, and slightly inverted, dispersion of valence band holes near the $Gamma$-point, which is found for up to $N propto 6$.
In this paper we review the theory of silicon nanowires. We focus on nanowires with diameters below 10 nm, where quantum effects become important and the properties diverge significantly from those of bulk silicon. These wires can be efficiently treated within electronic structure simulation methods and will be among the most important functional blocks of future nanoelectronic devices. Firstly, we review the structural properties of silicon nanowires, emphasizing the close connection between the growth orientation, the cross-section and the bounding facets. Secondly, we discuss the electronic structure of pristine and doped nanowires, which hold the ultimate key for their applicability in novel electronic devices. Finally, we review transport properties where some of the most important limitations in the performances of nanowire-based devices can lay. Many of the unique properties of these systems are at the same time defying challenges and opportunities for great technological advances.
We present first-principles calculations of silicene/graphene and germanene/graphene bilayers. Various supercell models are constructed in the calculations in order to reduce the strain of the lattice-mismatched bilayer systems. Our energetics analysis and electronic structure results suggest that graphene can be used as a substrate to synthesize monolayer silicene and germanene. Multiple phases of single crystalline silicene and germanene with different orientations relative to the substrate could coexist at room temperature. The weak interaction between the overlayer and the substrate preserves the low-buckled structure of silicene and germanene, as well as their linear energy bands. The gap induced by breaking the sublattice symmetry in silicene on graphene can be up to 57 meV.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
