Journal of Computational Electronics最新文献

In this paper, a highly efficient charge generation layer (CGL)-based blue organic light-emitting diode is proposed. The proposed device contains a CGL composed of two materials, 1,1-bis[(di-4-tolyamino)phenyl]cyclohexane (TAPC) and 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT-CN), which act as hole and electron injectors, respectively. The CGL in the proposed device is placed outside the emissive layer, which provides better luminescence and current as compared with four other CGL-based devices D₂, D₃, D₄ and D₅ where CGL is utilized below the cathode, above the anode, near both electrodes (cathode and anode) and inside the emissive layer, respectively. The proposed device exhibits noteworthy results, achieving peak current and luminescence values of 0.44 A and 3636.3 cd/m², respectively. The luminescence obtained is improved by about 16.8, 2.3, 1.7, 3, and 1.6 times compared with D₁, D₂, D₃, D₄ and D₅. Thickness optimization of the proposed device is also outlined. The optimized device shows maximum luminescence of 4670 cd/m².

In this investigation, we develop CdS-free non-toxic thin-film solar cell structure with antimony sulfide (Sb₂S₃) as an absorber material. Sb₂S₃ has found to be a promising candidate for production of renewable energy. Solar cells based on Sb₂S₃ have been attracted worldwide attraction due to their outstanding efficiency and low cost. To serve as an optimistic buffer layer, 3C-SiC (cubic silicon carbide) is used thanks to its suitable bandgap to replace toxic cadmium sulfide (CdS). SCAPS-1D (one-dimensional solar cell capacitance simulator) software has been employed to numerically investigate the performance of Sb₂S₃-based n-ZnO/n-3C-SiC/p-Sb₂S₃ heterostructure solar cells. The influence of absorber/buffer layer thickness, acceptor/donor densities, and defect density on device working have been investigated. Consequently, the role of defects in p-Sb₂S₃ along with the significance of n-3C-SiC/p-Sb₂S₃ interface defects has been studied to provide recommendations for achieving high efficiency. The proposed structure provides the enhanced efficiency of 17% under 1.5 G illumination spectrum. The parameters regarding solar cell performance such as V_oc, J_sc, FF, QE and η have been studied graphically. This novel structure may have considerable influence on progress of improved photovoltaic devices in future.

Nanomagnetic logic is a recent technology used in electronic devices and systems. The current challenge in circuit miniaturization has prompted a move away from the traditional metal-oxide-semiconductor technology. Nanomagnetic logic-based devices have no leakage current, and they are also non-volatile. In this paper, we propose run-time reconfigurable layout designs for the logic gates, and to show the applicability of the logic gates, we implement a single-bit comparator design. For the logic gate designs, we use slant-edge nanomagnets of different shapes as inputs. The proposed layout designs are verified using the MuMax3 micro-magnetic simulation tool, and results are compared with a previous approach. The implementation of a single-bit comparator design can significantly reduce the number of nanodots required, typically by (sim)50–80%, as well as the area occupancy, which can be reduced by (sim)56–99%.

First-principles calculations using the Hubbard approach (DFT + U) with PBEsol correlation were performed to compare the effects of incorporating 3d, 4d, and 5d metal atoms on the electronic and optical properties of m-HfO₂. Incorporating metal atoms in the HfO₂ crystal structure shifted the band gap edges and lowered the conduction band minimum, reducing the band gap as follows: 5.24 eV for HfO₂, 3.26 eV for HfO₂:Ti, 1.12 eV for HfO₂:W, and 0.92 eV for HfO₂:Nb. Total and partial density of states calculations showed that the valence band maximum of pristine HfO₂ is mainly constructed from O 2p states, while the conduction band minimum is mainly from Hf 4d states. For doped crystals, the conduction band minimum is mainly from 3d states of Ti, 4d states of Nb, and 5d states of W. For pristine HfO₂, the calculated dielectric constant, reflectivity and refractive index match available experimental and theoretical data. For doped systems, incorporating Nb (4d metal) and W (5d metal) had similar effects on the electronic and optical properties of HfO₂, differing more from incorporating Ti (3d metal). HfO₂ absorption roughly doubled upon Ti atom insertion (HfO2:Ti). Based on the results of this study, we would like to emphasize that these results provide a solid theoretical starting point that motivates further experimental studies into the application potential of these doped metal oxide systems.

The aim of this paper is to propose a compact device to design a multiplexer and demultiplexer which can reduce the circuit area while maintaining competitive performance. A novel device, the dielectric-separated independent-gate junctionless transistor (DSIG-JLT), is used to implement functional logic of a multiplexer and demultiplexer. The DSIG-JLT has four gates that can be electrically controlled in multiple ways to realize different digital logics. The DSIG-JLT is used to realize a 2 × 1 multiplexer and 1 × 2 demultiplexer by two different logic styles. The 2 × 1 multiplexer is implemented using four transistors, and the 1 × 2 demultiplexer is implemented using five transistors by NAND logic (logic style-1). Further, by using mixed logic, the 2 × 1 multiplexer is designed using three transistors, and the 1 × 2 demultiplexer using four transistors (logic style-2). A 4 × 1 multiplexer is also implemented using eight transistors. The propagation delay, rise time, and fall time of the 2 × 1 multiplexer (logic style-1) are calculated and are found to be 24.45 ps, 31 ps, and 8.2 ps, respectively, at a supply voltage (V_DD) of 1 V. It is found that with a change in supply voltage from 0.7 to 1.0 V, the delay, rise time, and fall time decrease by 17.2%, 11.4%, and 65.69%, respectively. Simulations are carried using the ATLAS 3D device simulator in mixed mode.

Graphical abstract

Solar energy is widely acknowledged as a promising and abundant source of clean electricity. Unfortunately, the efficiency of converting solar energy into electricity using photovoltaic (PV) systems is not yet satisfactory due to technical limitations. To improve this, it is essential to develop an accurate model that incorporates well-estimated parameters. However, the parameter identification process in the PV model is challenging due to its nonlinear and multi-modal characteristics. In this study, we propose a novel metaheuristic algorithm called the learning search algorithm (LSA) to address the parameter estimation problem in solar PV models. LSA utilizes historical experience and social information to guide the search process, thus enhancing global exploitation capability. Additionally, it improves the learning ability of the population through teaching and active learning activities based on optimal individuals, which enhances local development capability. The algorithm also incorporates a dynamic self-adaptive control factor to balance global exploration and local development capabilities. Experimental results demonstrate that our proposed LSA outperforms other comparison algorithms in terms of accuracy, convergence rate, and stability in parameter identification of PV models. Statistical tests confirm the superior efficiency and effectiveness of the LSA in parameter estimation. Moreover, our algorithm demonstrates competitive performance in solving real-world optimization problems with constraints. Overall, our study contributes to the improvement of solar energy conversion efficiency through the development of an accurate parameter estimation model using the LSA.

In this study, we employ density functional theory and the Siesta code to investigate the electronic and optical properties of beryllium oxide (BeO) zigzag nanotubes (n,0) with n = 6, 8, 10, 12, 14, 16. Our research aims to elucidate the characteristics of BeO nanotubes and their potential applications. Notably, we found that the bandgap energy of BeO nanotubes increases with diameter, indicating superior conductivity in smaller-diameter nanotubes. Our findings align closely with experimental data, particularly when using the GGA-WC functional. Additionally, we calculated nanotube buckling decrease with diameter, revealing its negligible impact on these structures. The static refractive index of BeO nanotubes remains consistent at approximately 1.1, with an optical absorption peak around 9 eV. Our research offers valuable insights into the electronic and optical properties of BeO nanotubes, which have implications for various applications.

An integral equation method is presented for the 1D steady-state Poisson-Nernst-Planck equations modeling ion transport through membrane channels. The differential equations are recast as integral equations using Green’s 3rd identity yielding a fixed-point problem for the electric potential gradient and ion concentrations. The integrals are discretized by a combination of midpoint and trapezoid rules, and the resulting algebraic equations are solved by Gummel iteration. Numerical tests for electroneutral and non-electroneutral systems demonstrate the method’s 2nd order accuracy and ability to resolve sharp boundary layers. The method is applied to a 1D model of the K(^+) ion channel with a fixed charge density that ensures cation selectivity. In these tests, the proposed integral equation method yields potential and concentration profiles in good agreement with published results.

To continue downscaling transistors, new materials must be explored. Two-dimensional (2D) materials are appealing due to their thinness and bandgap. The relatively weak van der Waals forces between layers in 2D materials allow easy exfoliation and device fabrication but also result in poor heat transfer between layers and to the substrate, which is the main path for heat removal, resulting in self-heating and thermal degradation of mobility. This study explores the electrothermal properties of five popular 2D materials (MoS₂, MoSe₂, WS₂, WSe₂, and 2D black phosphorous). We simulate various devices with self-heating with a range of gate and drain biases and examine the effects on mobility and change in device temperature. The effects are compared to the isothermal case to ascertain the impact of self-heating. We observe that Joule heating has a significant effect on temperature rise, layerwise drain current, and effective mobility. We show that black phosphorous performs the best thermally, owing to its relatively high thermal conductance to the substrate, while WSe₂ performs the best electrically. This study will inform future thermally aware designs of nanoelectronic devices based on 2D materials.

We investigate how the electronic and transport properties of six arm-chair graphene nanoribbon-based structures are modified with the introduction of symmetrical and asymmetrical geometrical V-cuts on their edges. A tight-binding model based on numerical non-equilibrium Green’s function method is used to compute the transport properties such as local density of states, transmission and current–voltage characteristics. We report the existence of nearly flat mid-bands for certain topologies after edge patterning. These bands give rise to non-zero transmission at low bias voltages. We uncover how this transmission varies with width, length, and biasing of the channel and also the temperature of the contacts. For structures in which flat mid-bands are absent, we show how their band gaps could be tuned by varying the width and length of the modified unit cells.