Papers by Keyword: Effective Mass

Abstract: In the present work, we studied dislocation amplitude-independent internal friction (AIIF) for segment of edge dislocation. Results obtained were compared with results of the Koehler-Granato-Lücke string model. Expression for dislocation effective rigidity and effective mass, obtained earlier by applying generalized susceptibility of dislocation, is used. Dependences of dislocation effective rigidity on dislocation segment length, dislocation effective mass on frequency and segment length, internal friction on for various values of frequency and segment length are plotted. Case of elastic interaction of the dislocation segment with pinning points is also investigated. It was found that main effect of elastic interaction the dislocation with the pinning points is reduces to influence in the effective rigidity. Plots of internal friction dependence on frequency for various values of distance between the dislocation and the pinning points are constructed.

Abstract: In this article, the effect of wire-size on the effective band gap of Silicon (Si) is analyzed. The band gap is one of the most significant electronic parameters of semiconductor material. The band gap of semiconductor depends on temperature, pressure, composition, number of atoms as well as on the size of the particle. When semiconductors are synthesized at nanoscale level, their small particle size gives rise to quantum confinement and the energy bands are split into discrete levels. It is observed that effective band gap of semi-conductor depends on the size of the wire (number of atoms and dimensions) and it increases by decreasing the size of Si nanowire. The size quantization effect is noticed as a shift of the effective band gap toward lower values with increasing temperature of Si nanowire which also shows increase in atomic vibrations. Keywords: Size effect; Energy band gap; Semiconductor, effective mass; nanowire.

Abstract: Electronic structure, effective masses and optical properties of monoclinic HfO₂ were studied using the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory (DFT). The calculated equilibrium lattice parameters are in agreement with the previous works. From the band structure, the effective masses and optical properties are obtained. The calculated band structure shows that monoclinic HfO₂ has indirect band gap and all of the effective masses of electrons and holes are less than that of a free electron. The peaks position distributions of imaginary parts of the complex dielectric function have been explained according to the theory of crystal-field and molecular-orbital bonding.