Search results

The purpose of this paper is to investigate the dependence of dark current on threading dislocations (TDs) in relaxed Ge layer for Ge/Si heterojunction photodetectors.

The analysis of the effects of TDs is based on SRH generation and recombination mechanism used in two‐dimensional drift‐diffusion numerical simulation.

It is found that the TDs in Ge layer acting as the recombination centers lead to large dark current densities of devices, and the recombination rate is affected by the impurity out‐diffusion from Si substrate. Besides, the TDs, being the acceptor‐like defects simultaneously, form band barrier at Si/Ge interface with lightly doped Si substrates, thus limiting the minority carrier transport and resulting in low dark current densities.

The simulation results are excellently consistent with the experimental data and indicate that the reduction of threading dislocation densities (TDDs), especially in Ge buffer layer, dramatically decreases dark currents densities of Ge/Si photodetectors. The investigation can be applied to imbue devices with desired characteristics.

To model the differential dc gain, base resistance, and current voltage performance of 4H‐Silicon Carbide (SiC) bipolar junction transistors (BJT) operating at and above room temperature. Accurate modeling will result in improved process efficiency, interpretation of experimental data, and insight into device behavior.

The PISCES two dimensional device simulation program is used to allow for modeling the behavior of 4H‐SiC BJT. The physical material parameters in PISCES such as carrier's mobility and lifetime, temperature dependent bandgap, and the density of states are modified to accurately represent 4H‐SiC. The simulation results are compared with the measured experimental data obtained by others. The comparisons made with the experimental data are for two different devices that are of interest in power electronics and RF applications.

The simulation results predict a dc current gain of about 25 for power device and a gain of about 20 for RF device in agreement with the experimental data. The comparisons confirm the accuracy of the modeling employed.

The simulated current‐voltage characteristics indicate that higher gain may be achieved for 4H‐SiC transistors if the leakage current is reduced.

The simulation work discussed in this paper complements the current research in the design and characterization of 4H‐SiC bipolar transistors. The model presented will aid in interpreting experimental data at a wide range of temperatures.

This paper reports on a new model that provides insight into the device behavior and shows the trend in the dc gain performance important for the design and optimization of 4H‐SiC bipolar transistors operating at or above the room temperature.

Renewable energy sources such as solar photovoltaic (PV) and wind are ubiquitous because of their lower environmental impact. Output from solar PV and wind turbines is unstable; hence, this article aims to propose an effective controller to extract maximum available power.

By focusing on the varying nature of solar irradiance and wind speed, the paper presents the maximum power point tracking (MPPT) technique for renewable energy sources, and power regulation is made by the novel inverter design. Moreover, a DC–DC boost converter is adopted with solar PV, and a doubly fed induction generator is connected with the wind turbine. The proposed MPPT technique is used with the help of a rain optimization algorithm (ROA) based on bi-directional long short-term memory (Bi-LSTM) (ROA_Bi-LSTM). In addition, the sinusoidal pulse width modulation inverter is used for DC–AC power conversion.

The proposed MPPT technique has jointly tracked the maximum power from solar PV and wind under varying climatic conditions. The power flow to the transmission line is stabilized to protect the load devices from unregulated frequency and voltage deviations. The power to the smart grid is regulated by three-level sinusoidal pulse width modulation inverter.

The methodology and concept of the paper are taken by the author on their own. They have not taken a duplicate copy of any other research article.

To adapt to the rapidly changing market environment, firms must constantly adjust and change their knowledge base to develop new technologies. The purpose of this paper is to analyze the improvement path of firms’ breakthrough innovation from the perspective of knowledge recombination in the context of dynamic change in the knowledge base. By analyzing the influencing mechanism of environmental dynamism on the relationship between the two, this paper provides a theoretical foundation for managers to make knowledge recombination decisions under a dynamic external environment while further enriching the firm’s innovation achievements.

Using data from 220 manufacturing firms listed on the Shanghai and Shenzhen A-share stock from 2010 to 2018, an extensive panel data set was constructed to investigate the effect of knowledge recombination, which was divided into recombination creation and recombination reuse, on firms’ breakthrough innovation. In addition, the authors differentiated environmental dynamism as market dynamism and technological dynamism and then examined its moderating role in the above relationships.

The research results show that various recombination behaviors of knowledge elements have a differentiated effect on firms’ breakthrough innovation presented as follows: Knowledge recombination creation is significantly positively correlated with firms’ breakthrough innovation, while knowledge recombination reuse is significantly negatively correlated with firms’ breakthrough innovation. In addition, environmental dynamism has a considerable moderating effect between knowledge recombination and firms’ breakthrough innovation further, emphasizing that the moderating effect on different types of knowledge recombination behaviors is significantly distinct.

First, given that this study refers to several Chinese noted databases to collect second-hand data for empirical analysis, future research could use first-hand data by collecting questionnaire survey and interview to provide a more practical and detailed research conclusion. Second, the authors focused on the contextual variable to explore the moderating role of environmental dynamism on the relationship between knowledge recombination and breakthrough innovation. Nevertheless, the indirect effects of other internal factors were not discussed. The authors advocate future studies to involve other moderators from employee social and phycological perspectives, such as trust in colleagues in the proposed theoretical models in this study.

This study is conducive for managers to attach great attention to knowledge management practices in the firm and to understand the critical role of knowledge recombination in affecting innovation performance under dynamic environmental changes. Moreover, this study provides practical guidance and serves as a reference for firms to strengthen their knowledge recombination ability as full utilization of existing knowledge elements and exploration of new knowledge values.

Primarily, from the perspective of dynamic changes in the knowledge base, this paper explores how the knowledge recombination behaviors affect firms’ breakthrough innovation, thereby enriching and extending the relationship theory between knowledge recombination capabilities and breakthrough innovation, while new and valuable ideas are provided in the study of issues related to the firms’ breakthrough innovation; Moreover, this study analyzes the moderating effects of diverse types of environmental dynamism on the relationship between knowledge recombination and firms’ breakthrough innovation from a multi-dimensional perspective proposing that the moderating effects of environmental dynamism on different knowledge recombination behaviors are distinct.

Numerical device simulation is developed to study the steady‐state and transient current‐voltage characteristics of double heterostructure AlGaAs/GaAs PNPN electro‐photonic device when its performance is influenced by the presence of interface and bulk recombination mechanism. The simulation results show that the holding current and voltage and the breakover point are strongly affected by varying the minority carrier lifetime at outer heterojunctions. Numerical results also indicate that shortening the minority carrier lifetime in the inner PN homojunction region only increases the OFF‐state current. These results are in agreement with experimental data on AlGaAs/GaAs PNPN devices. The numerical modelling approach taken in this study is shown to be essential in the design and optimization of PNPN switch.

An efficient device simulation method is presented, which has been derived from mapping the results of a complete two‐dimensional (2‐D) analysis onto an equivalent lumped element network. The method is currently being used to predict latch‐up sensitivities of CMOS process design.

The purpose of this paper is to discuss the effect of electric reverse stress currents on the performance of photovoltaic solar modules.

The effect of a reverse introduced current as a function of time is studied on the I‐V and C‐V characteristics and parameters which were extracted and analyzed using numerical analysis based on a reliable double exponential model.

The effect of an introduced reverse current for different periods simulated the effect of accumulated extreme reverse currents which may arise in solar cells and modules due to different reasons, causing dramatic changes in the shunt resistance as well as other characteristics, mainly when the time of the current application exceeded a certain limit.

The paper contributes to the research on the damaging effects of reverse currents on the normal operation of the solar cells and modules.

We have developed a two‐dimensional model for quantum‐well lasers which solves, self‐consistently, the semiconductor equations together with the complex scalar wave equation and the photon rate equation. To predict the threshold current accurately we have included the wavelength‐ and position‐dependence of the gain and the spontaneous emission. For the complex wave equation successive over relaxation (SOR) is used with two adaptive acceleration parameters for the complex wave amplitude and for the eigenvalue. Since the rate equation near threshold can be driven into divergence during iteration for a steady state solution, we have introduced a special damping technique to overcome this problem. Our model enables us to predict the characteristics of a quantum‐well laser with a minimal number of empirical constants. The output of the model includes light‐current characteristics, and the current and optical field intensity distributions. We show the results of a calculation for a graded‐index separate‐confinement heterostructure single quantum‐well (GRIN‐SCH SQW) laser.

This paper aims to study the effect of temperature on the process and kinetic parameters of the hydrogen evolution reaction of X80 under cathodic protection (CP) in 3.5% NaCl solution.

Potentiodynamic polarization combined with the hydrogen permeation test is used to analyze the hydrogen evolution reaction (HER) process and the rate-determining step for which is diagnosed through the electrochemical impedance spectrum method. Then, the influence of temperature on kinetic parameters of HER can be known from the results obtained by using the Iver-Pickering-Zamenzadeh model for data analysis.

The results show that the HER proceeds through Volmer–Tafel route with the Volmer reaction acting as the rate-controlling step; Increasing temperature gives a higher activity of the HER on X80, it also accelerates the hydrogen desorption and diffusion of hydrogen into the metal.

There exist few studies on the topic of how temperature affects the HER process. It is imperative to conduct a relevant study to give some instruction in cathodic protection system design and this paper fulfills this need.

Estimation of solar cell parameters, mathematical modeling and the actual performance analysis of photovoltaic (PV) cells at various ecological conditions are very important in the design and analysis of maximum power point trackers and power converters. This study aims to propose the analysis and modeling of a simplified three-diode model based on the manufacturer’s performance data.

A novel technique is presented to evaluate the PV cell constraints and simplify the existing equation using analytical and iterative methods. To examine the current equation, this study focuses on three crucial operational points: open circuit, short circuit and maximum operating points. The number of parameters needed to estimate these built-in models is decreased from nine to five by an effective iteration method, considerably reducing computational requirements.

The proposed model, in contrast to the previous complex nine-parameter three-diode model, simplifies the modeling and analysis process by requiring only five parameters. To ensure the reliability and accuracy of this proposed model, its results were carefully compared with datasheet values under standard test conditions (STC). This model was implemented using MATLAB/Simulink and validated using a polycrystalline solar cell under STC conditions.

The proposed three-diode model clearly outperforms the earlier existing two-diode model in terms of accuracy and performance, especially in lower irradiance settings, according to the results and comparison analysis.