High Second-Order Nonlinear Susceptibility Induced in GaN/AlxGa1 – xN Coupled Quantum Well for Infrared Photodectors Application

The second harmonic generation (SHG) of GaAs/AlxGa1 − xAs a wurtzite coupled quantum wells (CQWs) is studied theoretically for different widths of well, barrier and values Al concentration, taking into account the strain-induced piezoelectric (PZ) effects. The analytical expression of the SHG susceptibility is deduced by using the compact density matrix approach. The confined wave functions and energies of electrons GaN/AlxGA1 – x N are calculated in the effective-mass approximation, solving the Schrödinger equation by Numerov’s method using six order approximations for the derivatives. The calculated results also reveal that by adjusting the widths of well, the barrier and Al concentration respectively, a set of optimal structural parameters can be found for obtaining a strong SHG susceptibility. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2777

Absorption Coefficients of GaN / AlxGa1 – xN Core-Shell Spherical Quantum Dot

The total absorption coefficient in spherical GaN/AlxGa1 – xN core-shell nanodots is theoretically investigated taking into account effective mass approximation. The influence of the nanosystem geometry upon the energy spectrum and transition energy δE associated to interlevel transitions is studied. We found that the energy transitions vary with the core-shell radius, and the peak position of the total absorption coefficient is greatly affected by changing of the shell radius. The possibility of tuning the resonant energies by using the geometric core shell effect of the spatial confinement can be useful in the optoelectronic devices applications. Also we observed that the magnitudes of the total absorption coefficient can be increased significatly compared traditional cases of QD, and the peaks are shifted to the lower energies. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2960

FANO resonances in solid-fluid one and two dimensional systems

The gaol of this paper is to demonstrate that the propagation of acoustic waves in a single slab made of a homogeneous one dimensional (1D) solid embedded in a fluid at oblique incidence on a slab made of two dimensional (2D) rectangular rods immersed in a fluid, can exhibit transmission zeros near resonances the so-called Fano resonances

Numerical study of electrical characteristics of conjugated polymer light-emitting diodes

Conjugated polymers now provide a class of processible, film-forming semiconductors and metals. In this work, the electronic properties of polymer lightemitting diodes devices are numerically studied. Our results show how an insulating buffer layer with suitable thickness decreases the barrier height at the cathode and therefore increases the electron injection. We also discuss the effects from persistent charged traps

Schottky Diodes and Thin Films Based on Copolymer: Poly(aniline-co-toluidine)

Poly(aniline-co-o-toluidine) (PANI-co-POT) thin films were deposited on indium tin oxide- (ITO-) coated glass substrates by electrochemical polymerization under cyclic voltammetric conditions from aniline-co-o-toluidine monomer in an aqueous solution of HCl as a supporting electrolyte. These measurements showed that the optical band gap of the copolymer films is on the order of 2.65 eV. On the other hand, ITO/PANI-co-POT/Al devices were fabricated by thermal evaporation of Aluminum circular electrodes on the as-deposited PANI-co-POT films. The Current-Voltage characteristics of these devices are nonlinear. The diode parameters were calculated from I-V characteristics using the modified Shockley equation. The C-F characteristics were also measured

Dielectric Behavior of Ceramic (BST)/Epoxy Thick Films

Composite materials were made by mixing powders of Ba1−xSrxTiO3 (x=0.2 and 0.4) ceramics and epoxy resin with various volume fractions (vol%). Dielectric measurements of these composites were performed as a function of filler ratio in the range 100–360°K at 10 KHz. The dielectric constant of the composite increased with increasing volume fraction varies slightly with temperature. The 20 vol% of BST(0.4)-epoxy composite had the highest dielectric constant of 19.4 and dielectric loss tangent of 0.027. Among the dielectric mixing models presented, the model of Lichtenecker shows the best fit to the experimental data for both composites

Theoretical Analysis of Optical Gain in GaN / AlxGa1 – x N Quantum Well Lasers

In this study, we investigated numerically the effect of aluminum concentration, temperature and well width on optical gain GaN / AlxGa1 – xN quantum well lasers, taken into account effective mass approximation. The numerical results clearly show that the increasing of well width, and decreasing of temperature and Aluminum concentration, the optical gain increases

Electro-optic effect in GaN/Al₀.₁₅Ga₀.₈₅N single quantum wells for optical switch

he second-harmonic generation (SHG) susceptibility of wurtzite type gallium nitride with single quantum wells has been theoretically investigated in the framework of the compact-density-matrix approach. The confined wave functions and energies of electrons in GaN/AlxGa₁₋xN have been calculated in the effective-mass approximation, solving the Schrödinger equation by Numerov’s method using the second and fourth order approximations for the derivatives. The numerical results for typical GaN/Al₀.₁₅Ga₀.₈₅N quantum wells show that a strong SHG effect can be realized in electric field by choosing some optimized structural parameters