Advances in Condensed Matter Physics

The stannite structured ZnAg₂SnS₄ was developed from its parent composition ZnAg₂GeS4, which is considered to be an excellent photocatalytic material, as the demands for photocatalytic effect on organic and waste water treatment have been increasing around the globe. First and foremost, the geometry optimization was performed by density functional theory (DFT) of the generalized gradient approximation (GGA) with Perdew–Burke–Ernzerhof (PBE)-ballpark figured as the successful candidate for computational screening containing heavy metal complexes. The structural geometry parameters were determined along with the electronic band structure, density of state (DOS), partial density of state (PDOS), Mulliken charge population, elastic constant, and optical characteristics. When the Ge (ZnAg₂GeS₄) atom has been swapped out by a Sn (ZnAg₂SnS₄) atom, the changes in band gap is noticeable, which rises from 0.94 eV to 1.15 eV with the same geometry and surface area. But, after 7% Fe doping, it has decreased to 0.32 eV. The PDOS demonstrates that the production of hydrogen for photocatalytic influence on wastewater treatment is dependent on the Fe atom's ability to induce and boost the electron density in both the conduction band and the valence band. The study of the elastic constant and mechanical constant revealed that these crystals are extremely stable in any environment. The dielectric constant and optical absorptions illustrate the superior evidence for photocatalytic activity. To sum up, it could be said that after doping of Fe, the elastic constant and mechanical constant show all universal anisotropic index crystals and ZnAg₂Sn_0.93Fe_0.07S₄ can absorb a variety of UV radiation, which raises the possibility that it could function as a photocatalyst.

To examine the effects of the nonlocal thermoelastic parameters in a nanoscale semiconductor material, a novel nonlocal model with variable thermal conductivity is provided in this study. The photothermal diffusion (PTD) processes in a chemical action are utilized in the framework of the governing equations. When elastic, thermal, and plasma waves interact, the nonlocal continuum theory is used to create this model. For the main formulations to get the analytical solutions of the thermal stress, displacement, carrier density, and temperature during the nanoscale thermo-photo-electric medium, the Laplace transformation approach in one dimension (1D) of a thin circular plate is utilized. To create the physical fields, mechanical forces and thermal loads are applied to the semiconductor’s free surface. To acquire the full solutions of the research areas in the time-space domains, the inverse of the Laplace transform is applied with several numerical approximation techniques. Under the impact of nonlocal factors, the principal physical fields are visually depicted and theoretically explained.

The manuscript substantiates the structural and electronic properties of covalent triazine frameworks (CTF)/As van der Waals heterostructures (vdWh) employing the standard first-principles calculation method. The numerical results designate that the CTF/As vdWh has robust crystal structures, a type-II band alignment (BA), and an indirect bandgap of 1.44 eV. The calculated results demonstrate that the strain could lead to interesting indirect-direct semiconductor transitions, while the external electric field could give rise to type-II to type-I BA and semiconductor-metal transitions. The underlined outcomes present the workability of CTF/As vdWhs in unprecedented high-performance optoelectronic equipment.

In this study, the structural, electronic, elastic, phonon vibration, thermodynamic features, and optical properties of the orthorhombic phase of (space group Pnma) were examined by first-principles calculations utilizing the plane wave ultrasoft pseudopotentials in generalized gradient approximations (GGAs) and with Hubbard on-site correction (DFT + U). To improve the value of the band gap, the exchange correlation potential is also approximated with Hubbard correction (GGA + U). The equilibrium state properties such as lattice parameters, unit cell volume, bulk modulus, and its derivative were calculated and are in good agreement with the existing data. The mechanical properties such as bulk modulus, shear modulus, Young’s modulus, and elastic anisotropy were determined from the obtained elastic constants. The ratio of bulk modulus to shear modulus confirms that the orthorhombic phase of is a ductile material. In addition, the longitudinal sound velocity, transverse sound velocity, and Debye temperature for have been computed. The absence of negative frequencies in the phonon dispersion curve and the phonon density of states confirm that in the orthorhombic phase is dynamically stable. The thermodynamic parameters such as free energy, entropy, and heat capacity were examined with variations in temperature. Finally, the absorption coefficient, dielectric constant, energy loss function, reflectivity, and refractive index are discussed in detail in the spectral range 0–1.6 Ry (21.77 eV). The polarizations along (100), (010), and (001) directions significantly show different optical responses.

Ternary boron-carbon-nitride compounds are the hardest, chemically stable, and most applicable semiconductors in optoelectronic devices. We investigate the quasi-particle and excitonic properties of type II o-BC₂N using many-body perturbation theory (MBPT). The state-of-the-art GW and BSE methods were used to determine the accurate band gap and excited-state characteristics of this material. We simulate the convergence test and structural optimization in DFT, which is the starting point for the GW calculation. We also compute the convergence test of the parameters in GW and BSE. As a result, the bandgap of our system is found to be 2.31 eV and 1.95 eV using the GW approximation and DFT-PBE, respectively. Since the valence and conduction band edges are located at different Brillouin zones, we decide that o-BC₂N is an indirect bandgap semiconductor. In addition, by applying the scissor operator, we corrected the quasi-particle bandgap, which shows almost the same result as the GW approximation. Furthermore, using the BSE algorithm, we calculate the optical bandgap of type II o-BC₂N to be 4.0 eV with the excitonic effect and 4.4 eV without the excitonic effect. The highest peaks of the imaginary dielectric function with the excitonic effect shift to a lower energy level at 11 eV than without the excitonic effect at 13.5 eV. The electron charge distribution is computed by fixing the hole position. Finally, we suggest that type II o-BC₂N is promising for the application of optoelectronic semiconductors.

TiO₂ nanoparticles (NPs) were produced via utilized nanosecond laser ablation of titanium in water. The description of these NPs was employed utilizing XRD, SEM, and UV-VIS. Then, optoelectronic properties were investigated via a drop-casting of TiO₂ NPs on the Si wafer substrate. XRD results show the formation of anatase TiO₂. The SEM exhibits a spherical shape with sizing changing from 5 nm to 50 nm. The bandgap was 3.6 eV which was determined from the Tauc chart. The IV characteristic of the TiO₂NPs/Si heterojunction showed good rectifying behaviour, with a maximum responsivity of about 0.7 A/W at 310 nm.