Effect of electron temperature in a magnetized plasma sheath using kinetic trajectory simulation

The understanding of the properties of magnetized plasma sheath has been various beneficial applications in surface treatment, electron emission gun, ion implantation, and nuclear fusion, etc. The effect of electron temperature on the magnetized plasma sheath has been studied for a fixed magnetic field and ion temperature. It has been observed that various plasma sheath parameters can be prominently altered by the varying temperature of the electron. The density of ion is influenced more by the change in electron temperature rather than the electron density. The temperature of the electron has a great effect at the wall, when electron temperature increases, the ion and electron densities at the wall decreases. This shows the potential at the wall also decreases follows the Poisson’s equation. Similarly, the electric field also decreases but total charge density increases when the electron temperature is increased. BIBECHANA 18 (2021) 58-66

First-Principles Calculations on Atomic and Electronic Properties of Ge/4H-SiC Heterojunction

First-principles calculation is employed to investigate atomic and electronic properties of Ge/SiC heterojunction with different Ge orientations. Based on the density functional theory, the work of adhesion, relaxation energy, density of states, and total charge density are calculated. It is shown that Ge(110)/4H-SiC(0001) heterointerface possesses higher adhesion energy than that of Ge(111)/4H-SiC(0001) interface, and hence Ge/4H-SiC(0001) heterojunction with Ge[110] crystalline orientation exhibits more stable characteristics. The relaxation energy of Ge(110)/4H-SiC(0001) heterojunction interface is lower than that of Ge(111)/4H-SiC(0001) interface, indicating that Ge(110)/4H-SiC(0001) interface is easier to form at relative low temperature. The interfacial bonding is analysed using partial density of states and total charge density distribution, and the results show that the bonding is contributed by the Ge-Si bonding.

First-Principles Study on Energy Property and Stability of Y3Al5O12 Crystal

The geometrical structure of Y3Al5O12 (YAG) crystal was optimized by using first-principles calculation scheme, i.e. generalized gradient approximation (GGA) with the PW91 exchange correlation potential and “on the fly” pseudo-potential (OTFPP). The obtained lattice parameters are in good accordance with experimental results reported in the literature. This confirms the validity of the present GGA-OTFPP scheme. The total energy, populations, and contour maps of total charge density of YAG system were calculated with the same scheme. The derived formation energy (-2.396eV) indicate the good stability of the structure. The obtained Mulliken charge populations of atoms, overlap populations, as well as contour maps of total charge density congruously show that YAG crystal is a mixed bond material with stronger ion bond and weaker covalence bond.

First-Principles Study of the Properties of Clean and Ni-Doped TiC/Fe Interfaces

First-principles plane-wave pseudopotential calculations of the electron structure and energetics of the interfaces of clean and Ni-doped TiC/Fe are reported. We predicted the atomic structure, bonding, and the interface binding energy of TiC(100)/Fe(100) and TiC(100)/Fe(110). By comparing the interface bonding energy and the total charge density distribution, the interface have priority to combine in TiC(100)/Fe(100) and TiC(100)/Fe(110) ways, where the former’s interface binding energy is higher. So the structure of TiC(100)/Fe(100) is more stable. The doped Ni atoms have preferential access to Fe-based body and form FeNi alloy, and enhance the interface bonding energy, thus effectively reducing the system energy of TiC(100)/Fe(100) and TiC(100)/Fe(110) interfaces, increasing the bonding strength and stability of interfaces of the composite materials.

Adduct formed by chromium trioxide and zwitterionic quinolinic acid

Chromium trioxide forms an adduct with zwitterionic quinolinic acid. The structure of the product was found to be (quinolinium-3-carboxylato-O)trioxidochromium(VI), determined by single-crystal X-ray diffraction methods. To evaluate the bonding properties of the compound, its structure was optimized at the B3LYP/6-311G* level of theory. The electronic characteristics were investigated by topological methods applied to the total charge density in various model compounds including the title compound, title compound with a HF molecule presenting a hydrogen bonding and anionic moiety. Calculated aromaticity indices indicate that the quinolinic rings tend to conserve their degree of aromaticity against hydrogen bonding. However, when there is hydrogen bonding involving an N-H bond or when the quinolinium zwitterion is deprotonated, there are clear changes in the interaction between chromium trioxide and the quinolinic moiety.

Comparison of Inversion Layer Electron Transport of Lightly Doped 4H and 6H SiC MOSFETs

nversion layers of 4H and 6H Silicon carbide based MOS devices are characterized by Gated Hall measurements to determine the trap density close to the conduction band edge and the main scattering mechanisms that limit the mobility. MOS gated Hall structures were fabricated on 4H SiC polytype with p-type doping of 5X1015cm-3 and 2X1017cm-3. MOS Gated Hall structures were also fabricated on 6H SiC polytype with p-type doping of 7.5X1015cm-3. The gate oxide was grown thermally with N2O as a precursor followed by a NO post oxidation anneal. The inversion layer Hall mobility on the 6H SiC MOSFET sample decreased with increasing temperature from room temperature to 423K, while on the 4H SiC MOSFET samples the inversion layer mobility increased slowly. Approximately 50% of the total charge density at the interface of both 6H and 4H SiC MOSFETs was found to be trapped charge. The dominant scattering mechanism in 6H SiC MOSFETs was inferred to be phonon scattering based on the temperature dependence and theoretical estimates of the phonon limited mobility. In the case of 4H SiC, we infer that at surface roughness scattering is the dominant scattering mechanisms at high surface fields.

Study of Spectral and thermal properties of Selenium Diatomic Halides by Semi-empirical Treatment

The spectroscopic properties, potential energy curve, dipole moments, total charge density, Electrostatic potential as well as the thermodynamic properties of selenium diatomic halides have been studied using code Mopac.7.21 and hyperchem, semi-empirical molecular orbital of MNDO-method (modified neglected of differential overlap) of parameterization PM3 involving quantum mechanical semi-empirical Hamiltonian. The relevant molecular parameters like interatomic distance, bond angle, dihedral angle and net charge were also calculated.

Electronic and Optical Parameters of the TGM-3 Photopolymer

Molecular properties of the TGM-3 photopolymer have been investigated using a HYPERCHEM 4.0 computer package. The geometry of this photopolymer was successfully optimized and the TGM-3 structure obtained shows a very complicated non-linear shape. The total charge density of TGM-3 is strongly nonuniform. C=O double chemical bonds are roughly perpendicular to a bent central chain. We have calculated a value of the HOMO–LUMO energy gap which is not in agreement with our experimental data for the fundamental absorption edge. A possible origin of this difference is suggested. One can expect that the TGM-3 properties have a strong influence on its solid many-component mixtures with other photopolymers.

High precision measurement of Debye-Waller factors for NiAl

Motivation Quantitative convergent beam electron diffraction (CBED) is increasingly appreciated as a tool to determine bonding charge densities of crystalline materials. Simulated CBED patterns are fitted to experimental ones to derive the structure factors. These are converted by means of the Mott formula to yield the total charge density. Finally a neutral atom total charge density is subtracted and the difference is interpreted as the bonding charge density. Accounting for the temperature by a Debye-Waller factor (DWF) the g-th Fourier coefficient of the bonding charge density is then given by where u denotes the thermal root mean square atomic displacement. Here we have assumed thesimplest case of identical isotropic atomic vibrations for all atoms in the crystal. In order to estimate the error in due to the uncertainty in u we insert the results obtained by Fox and Tabbernor for NiAl at room temperature. They found differences between atomic and measured values of in the order of 2 percent.