The Current Carriers’ Dispersion Law of a Crystal, Their Chemical Potential and a Set of Important Properties of Crystals

In this paper, a new non-parabolic dispersion law has been established, which for a small parameter of the spectrum nonparabolicity coincides with the known Kane’s nonparabolic dispersion law. The Kane’s dispersion law works well when the well-known parameter of nonparabolicity is much less than 1, and the new law works well enough when the parameter of nonparabolicity is less than 1. In addition, this law shows that crystals with a band gap (i.e., forbidden band width) Eg~10-1 eV – these are semiconductor crystals, crystals with Eg~10-2 eV – these are metals.

The Important Questions of Statistical Theory of the Crystals' Thermal and Kinetics Properties

In this paper, the short algorithmic formulas for computations of the crystals thermal and kinetic properties are given. These formulas are fulfilled the case of isotropic crystals for any one of dispersion laws of current carriers, where these carriers can be scattered by all kinds of the crystal lattice defects. In the paper, these algorithmic formulas were used to calculations the important properties of crystals with the nonparabolic Kane’s dispersion law of current carriers. Here, the passing from these non-parabolic dispersion law crystals to the parabolic dispersion law crystals was also described.

Directional Goldstone waves in polariton condensates close to equilibrium

Quantum fluids of light are realized in semiconductor microcavities using exciton-polaritons, solid-state quasi-particles with a light mass and sizeable interactions. Here, we use the microscopic analogue of oceanographic techniques to measure the excitation spectrum of a thermalised polariton condensate. Increasing the fluid density, we demonstrate the transition from a free-particle parabolic dispersion to a linear, sound-like Goldstone mode characteristic of superfluids at equilibrium. Notably, we reveal the effect of an asymmetric pumping by showing that collective excitations are created with a definite direction with respect to the condensate. Furthermore, we measure the critical sound speed for polariton superfluids close to equilibrium.

Evaluation of resisdence time measurements on heat exchangers for the determination of dispersive Peclet numbers

The recently developed special unity Mach number dispersion model prescribes the corrections to heat transfer coefficients which are simple functions of the dispersive Peclet numbers. They can be determined through the residence time measurements. An evaluation method is described in which the measured input and response concentration profiles are numerically Laplace transformed and evaluated in the frequency domain. A characteristic mean Peclet number is defined. The method is also applied to the parabolic dispersion model and the cascade model. A calculated example of a tube bundle with maldistribution and backflow demonstrates the suitability of the evaluation method.

A Theoretical Model of Band-to-Band Tunneling Current in an Armchair Graphene Nanoribbon Tunnel Field-Effect Transistor

Tunneling current in an armchair graphene nanoribbon (AGNR) tunnel field-effect transistor (TFET) was modeled. A linear equation was employed in describing a potential distribution within the AGNR due to its simplicity. A parabolic dispersion and an electron effective mass obtained by approximating kx 0 to the parabolic dispersion were applied to AGNR. In order to obtain electron transmittance, electron wavefunctions in AGNR were based on Airy functions. The obtained transmittance was then applied to calculate the tunneling current by employing the Landauer formula. The calculated results showed that the tunneling current increases with the AGNR width. It was also shown that the tunneling current increases as temperature decreases. In addition, the gate voltage influences the saturation condition of tunneling current in AGNR TFETs.

Electronic structure and transport properties of ternary skutterudite: CoX3/2Y3/2

Electronic properties of ternary skutterudites AX3/2Y3/2 (A=Co, X=Ge, Sn and Y=S, Te) are investigated using first principles calculations to clarify recent experimental results. Band derivatives are computed accurately within an approach based on Maximally Localized Wannier Functions (MLWFs). Band structures exhibit larger effective masses compared to parental binary CoSb3. Our results also indicate a more parabolic dispersion near the top of the valence band and a multivalley character in both conduction and valence band. Despite the improved thermopower these skutterudites has relatively low power factor due to increased resistivity. The fundamental cause of such large resistivity seems to be associated with the ionicity of the bonding.