Journal of Interface, Thin Film and Low Dimension Systems
Volume:4 Issue: 1, Summer-Autumn 2020

In this paper, a numerical model is used to analyze photovoltaic parameters according to the electronic properties of InGaN/GaN multiple-quantum-well solar cells (MQWSC) under hydrostatic pressure. Finite difference techniques have been used to acquire energy eigenvalues and corresponding eigenfunctions of InGaN/GaN MQWSC, where all eigenstates are calculated via a 6×6 k.p method under applied hydrostatic pressure. All symmetry-allowed transitions up to the fifth subband of the quantum wells (multi-subband model) with barrier optical absorption are considered. The linewidth due to the carrier-carrier and carrier-longitudinal optical (LO) phonon scattering are also considered. A change in pressure up to 10 GPa increases the intraband scattering time up to 38 fs for heavy holes and 40 fs for light holes. The raise in the height of the Lorentz function reduces the excitonic binding energy and decreases the radiative recombination rate up to 0.95×1025 cm-3S-1.  The multi-subband model has a positive effect on the radiative recombination rate.

In this study, we investigate the dynamics of the Entanglement in a two-spin system with long-range interaction.

For this purpose, we use negativity as the entanglement measurement. Using the time evolution operator, we obtain entanglement dynamics of the system at time t. We consider two different initial states and investigate the dynamical behavior of the system for all of them separately. Finally, we consider both J and D as a function of R and then study the time evolution of the entanglement in different R.

We find that in the long-range interaction, the R dependence of the dynamical behavior in the two systems is different. Depending on the initial states, the DM interaction and the magnetic field have no effect on the entanglement dynamics.

The pulsed laser deposition is a practical synthesis route because of its unique advantages in growing various materials. Furthermore, the quality of thin films depends on different parameters in the deposition process. Meanwhile, ZnO has many applications in manufacturing optics, electronics, and optoelectronics instruments because of its exclusive properties. We have set up a PLD array to deposit the ZnO thin films on glass substrates. This study investigates the structural and optical characteristics of the films deposited at two different pulse repetition rates. Based on the optical-microscopic images and the scanning electron microscope (SEM) micrographs of films, increasing pulse repetition rate increases the uniformity of the particle size distribution and enhances film thickness. Also, the optical characterization performed by UV-Visible spectroscopy shows that the absorption and transmission rate, bandgap energy, and crystalline quality of the films can adjust by tuning the pulse repetition rate.

Spin-orbit interactions of exciton relativistic bound states at a finite temperature in the framework of the projective unitary representation in a physics model with the Coulomb potential have been investigated. The ground state of the system in order to describe the temperature effect in a low dimension environment has been defined. The bound state, with electron-hole pair, has attracted a great deal of interest in thin films and nanophysics. The reality of the state has been the subject of intense concern among theoreticians and experimenters in recent years. Spin-orbit interactions of exciton are considered to be in an electron-hole pair bound state. The problem of spin interactions of coupled states based on the quantum field theory in its widest sense is a method to control and achieve reasonable goals; and in this article, the problem is examined in detail. The structure of the interaction Hamiltonian with the Coulomb type potential at finite temperatures is defined and then the mass and energy spectra of an exciton based on the spin interactions are determined theoretically. The defined properties at finite temperature can be used for new high technology materials of semi-conductive features for electronics, microelectronics, photovoltaic or solar cell manufacturing, and semiconductor chips.

In this research, ZnSe thin films were deposited on glass substrate by the thermal evaporation method with deposition rates of 0.2, 0.4, 0.6, and 0.8 nm/s and with a constant thickness of 250 nm. All samples were annealed for 100 minutes at a temperature of 400 °C. Various techniques such as UV–Vis spectrophotometer, X-ray diffraction (XRD) analysis, and scanning electron microscope (SEM) were used to investigate different physical parameters such as energy band gap, refractive index, extinction coefficient, dielectric constant, and porosity of the ZnSe thin films.  The influence of the deposition rate on the mentioned parameters was investigated. The XRD patterns showed that the ZnSe thin films have a cubic structure. The structural parameters such as lattice constant, crystallite size, strain, and dislocation density were determined for different samples. The maximum average transmittance of %93.1 in the visible wavelength region was obtained for the deposition rate of 0.6 (nm/s). The optical band gap was calculated using the derivation of absorption spectrum fitting (DASF) method, and the values of the energy bandgap were obtained in the range of 3.710.01 to 3.980.01 eV. The XRD results acquired from the Williamson-Hall method showed that the crystallites size and strain of different samples were achieved in the range of 21.61.1 to 42.92.3 nm and (0.610.02)×10-3 to (2.890.04)×10-3, respectively. Finally, the relation between the optical and microstructural properties of the ZnSe films was studied.

The ternary titanium chromium nitride (TiCrN) thin film on Si (100) substrate without any external temperature was deposited by radio frequency (RF) magnetron sputtering. The substrate was kept at a distance of 35 mm from the target. The growth morphology, crystalline structure, roughness, contact angle, and thickness of the coatings were studied as a function of the input RF power and negative bias voltage. The grazing incident X-ray diffraction (GIXRD) results show that TiCrN diffraction peaks appeared only in samples with substrate bias = -70 V. The surface morphology was investigated by Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). The films change from hydrophilic to hydrophobic with the increase of negative bias voltage. The roughness and contact angle of the samples increase with the decrease in the RF power from 300 W to 200 W. In both cases (a) and (b), the deposition rate increases as a result of an increase in the target power.