Journal of Computational Electronics最新文献

The formation of metal dichalcogenide heterostructures enables tailoring their properties for future optoelectronics and energy storage. The current paper focuses on the study of the effect of interlayer spacing on the electronic and optical properties of SnS₂/graphene/SnS₂ sandwich heterostructure, using density functional theory electronic structure calculations. We find low cohesive energies/ per atom ((0.0506 to 0.0514) eV) for all the various interlayer spacing configurations (1–5 Å) considered in this study, implying the feasibility of experimental realization. The Mulliken charge transfer analysis suggests negative to positive net charge ((-0.12 to 0.18)) transfer for 1–3 Å threshold interlayer spacing, which implies acceptor and donor charge transfer configurations. The density of states of SnS₂/graphene/SnS₂ retains unoccupied states for all the interlayer spacing configurations, which can be attributed to localized exciton states and strong electronic coupling between the electrons within the heterostructure layers. We further find a strong optical response and localized electronic transport, which can pave the way for optoelectronic applications of this material heterostructure.

We propose an original design for a HgCdTe-based terahertz vertical-cavity surface-emitting laser with twenty 5 nm HgTe quantum wells. Feasibility of laser generation at 9 THz and a lattice temperature of 8 K is shown. The estimate of the threshold pump intensity using laser radiation at a wavelength of 5 μm is 3 W/cm², which makes it possible to expect continuous wave (CW) mode lasing. Such a low required pump intensity will make it possible to create a very compact system of a laser pumped by CW mid-infrared quantum cascade laser.

OLED technology, a revolutionary approach to display and lighting, offers thin, flexible, and vibrant solutions that redefine the visual experience in various devices. External quantum efficiency, a key metric, provides valuable insights into how effectively these devices convert electrical energy into light, guiding efforts to enhance efficiency and optimize OLED technology. This crucial factor, often affected by charge imbalance, non-radiative processes, energy losses, material limitations, device architecture, and design, can be significantly improved. The choice of material selection can impact the ability of the OLED to convert injected charges into light effectively. The transport layers facilitate the movement of charge carriers (electrons and holes) within the device, influencing light emission efficiency. In this proposed work, the introduction of organic materials in electron and hole transport layers can potentially improve the external quantum efficiency by up to 11.2%, a significant advancement that can be analyzed through electrical and optical characterization.

A direct current (DC) compact model for negative capacitance field-effect transistors (NCFETs) based on a metal-ferroelectric-insulator-semiconductor (MFIS) structure is proposed, considering the influence of deep-level interface trap states. To overcome the bottleneck problem of accurately and efficiently solving models, an explicit algorithm is developed, which is used to solve the complex Landau–Devonshire (LD) formula for the second-order phase transitions in physical models and the transcendental equation of trap density of states and surface potential. Compared with existing algorithms based on analytical surface potential, the new method does not require the numerical methods involving several iterations to obtain more accurate results, and the model can accurately reflect the opposite control effect of interface traps on surface potential and current under different ferroelectric (FE) thicknesses. The high precision of the model was verified through comprehensive numerical calculations and experimental data, indicating that the model can be effectively applied to circuit simulation design under low-power condition.

Density functional theory (DFT) has sparked intense interest in computational material predictions, especially in electronic band structure, optical dielectric functions, elastic moduli, and phonon calculations using non-local hybrid functionals. Using the first-principle-based calculations, a wide direct Γ-Γ bandgap E_g of 2.68 eV has been reported. Our partial density of states (PDOS) data also demonstrate that the substance exhibits metallic properties, based on the nonzero density of states at Fermi-level E_F. Still, what is more, our computational data show the orbital hybridization between Ge 4s² and S 3p⁴ electron states on the valence level, and a strong repulsive force occurs on both Ge and S p electron orbitals. The optical absorption coefficient calculated can reach up to 3 × 10⁵ cm⁻¹, indicating good material absorption. Our elastic information provided predicts substance ductility and ionic-covalency of the group IV-VI material. We have also added Vickers hardness and machinability index to our publication, for the sake of completeness. Finally, the slight system instability and weak coupling of the GeS₂ material have been observed, according to our phonon dispersion and density of phonon states plot.

This current study focuses on predicting the electronic and magnetic behaviors of WCl₃ monolayer when subjected to an external electric field. Unlike CrI₃, the WCl₃ monolayer displays a preference for an antiferromagnetic (AFM) ground state with an in-plane easy axis. This AFM state remains consistent across the entire spectrum (0–1 V/Å) of the external electric field. The indirect electronic band gap of the WCl₃ monolayer is predicted to be about 2.16 eV. Through our analysis, we’ve identified that the dominance of the valence band maximum and the conduction band minimum stems mainly from the ({d}_{{x}^{2}-{y}^{2}}) orbital (52% contribution) and the ({d}_{{z}^{2}}) orbital (97% contribution) respectively, attributed to the W element. The majority of electronic transitions related to the band gap arise due to these specific orbitals. Furthermore, the application of an external electric field can adjust the band gap to zero, prompting a transition from semiconductor to metal at an electric field intensity of E = 0.9 V/Å. Using mean field theory, we estimate the Neel temperature (T_N) of the AFM system to be approximately 356 K, a notably high value surpassing room temperature. Moreover, the application of an electric field demonstrates the potential to further elevate the Neel temperature, crucial for the functionality of high-temperature spintronic devices. Our comprehensive examination also delves into the magnetic anisotropy of the WCl₃ monolayer. The analysis of magnetic anisotropy energy (MAE) indicates that, contrary to the CrI₃ monolayer, the transition metal W significantly contributes to the system’s MAE, which is predicted to be − (3.44text{ meV}/text{W}). The magnetic easy axis aligns along the (x) direction (in-plane).

This work investigated a method for improving the efficiency of solar cells through the incorporation of carbon nanotubes (CNTs), which were used as the absorber layer of the solar cell. The CNTs were generated using plasma-enhanced chemical vapor deposition (PECVD). The use of the PECVD-generated CNTs in the absorber layer of the solar cell was found to increase the electrical conductivity due to the introduction of a large number of free charge carriers in the form of electrons and holes. We were thus able for the first time to estimate a relation between plasma variables and the efficiency of the proposed solar cell. The results showed that an increase in electron and ion density resulted in an increase in the efficiency of the solar cell, whereas an increase in electron and ion temperature led to a decrease in efficiency. We also studied the variation in efficiency in relation to the absorber layer of the proposed solar cell structure. The results obtained were consistent with those from previous studies based on solar cells.

Density functional theory (DFT) methods are employed to investigate the capability of B₃₆ borophene nanosheets as sensors for detecting the bromoacetone (BCT) molecule. An evaluation of the structural and electronic properties of both BCT and B₃₆ borophene is conducted. Subsequently, through computed metrics such as adsorption energy, charge density difference, and density of states, the interaction between B₃₆ and the BCT molecule is examined via dispersion-corrected density functional theory (DFT). Employing the reduced density gradient approach for the analysis of non-covalent interactions, we further explored the nature of these interactions. The obtained results illustrate that B₃₆ borophene nanosheets serve as effective sensors for the BCT molecule, showcasing their ability to adsorb up to five BCT molecules through an exothermic process. BCT molecules chemiadsorb onto B₃₆ borophene by forming B‒O covalent bonds, engaging the oxygen atom of the carbonyl group in BCT with the edge boron atoms of B₃₆ borophene. Additionally, BCT molecules physio-adsorb on both the concave and convex sides of B₃₆ borophene, facilitated by van der Waals interactions. Ab-initio molecular dynamic simulations confirm the thermal stability of the BCT@B₃₆ concave and convex complexes at both 300 K and 400 K.

The energy-loss tensor of bilayer and monolayer graphene is calculated according to the model expressed in Su et al. (Phys Rev Lett 42: 1698 1979). The size and geometry of the nanoscale carbon systems play an important role in their optical properties. Absorption bands of bilayer and monolayer graphene in the 2.81–8.0 eV region indicate sharp structures in each band. The molecular structure of these bands is localized and their crystalline order is long-range. In the x-direction of the electric field, the dielectric tensor and the energy-loss tensor of bilayer and monolayer graphene have the maximum amount. The importance of results for diamond, fullerene, graphite, and graphene is discussed.