This paper presents an efficient ensemble Monte Carlo approach for simulating electron transport in silicon-based semiconductors. The proposed model incorporates key scattering mechanisms—impurity, acoustic phonon, and nonpolar optical phonon interactions—by calculating their respective scattering rates, determining the probability of each scattering event, and assigning post-scattering energies and angles according to appropriate distributions. A three-valley framework is employed to account for anisotropy and conduction-band non-parabolicity, with direction-dependent effective masses and wave vectors, ensuring accurate simulation of electron transport under high electric fields. Key findings reveal fundamental transport characteristics: drift velocity shows linear dependence in weak fields, followed by saturation at higher fields due to increased scattering. Temperature increases cause reduced peak velocities and longer relaxation times, while higher impurity concentrations gradually decrease peak velocity through enhanced Coulombic scattering. Notably, significant velocity overshoot occurs at high fields (10-50 kV/cm), where electrons exhibit temporary velocity enhancements before stabilization. This arises from electrons entering high-energy states where momentum loss exceeds energy loss, with overshoot magnitude increasing with field strength. The study identifies a threshold field of ~30 kV/cm and validates results against Silvaco software (<5% deviation), experimental data, and other numerical methods. The model's novelty lies in capturing both steady-state and transient behaviors across varying temperatures, with the provided simulation code enhancing reproducibility. This framework offers robust analysis for designing high-speed silicon devices.
This study used a numerical model to investigate the internal quantum efficiency in InGaN/GaN multiple-quantum-well light-emitting diodes (MQWLEDs) under varying temperatures and hydrostatic pressures. Our calculations demonstrated that a temperature change could increase the carrier capture coefficients, while a change in pressure could decrease them in the quantum well. It was further found that the carrier-LO phonon coupling of heavy holes made the smallest contributions to hole capture coefficients. Based on these results, radiative and non-radiative recombination (i.e., Auger and Shockley-Read-Hall) and carrier leakage current decrease with increasing pressure and increase with increasing temperature. Increasing pressure by 10 GPa increases the quantum efficiency, while increasing temperature in the range of 300-600K has the opposite effect, decreasing it. Comparing this model with other models and experimental data demonstrates the good validity of this model, particularly in light of the multiphonon model. Generally, increasing temperature has a negative effect and increasing pressure has a positive role on the internal quantum efficiency.
In this study, a comprehensive analysis of the electronic energy spectrum and refractive index variations in semiconductor quantum dots is presented. Using the matrix formalism, the relationship between the linear refractive index and carrier concentration is systematically derived. Numerical calculations are carried out for a GaAs/AlₓGa₁₋ₓAs quantum dot heterostructure to explore how optical excitation intensity, dot size, and alloy composition influence the energy levels and optical response. The results demonstrate that these parameters significantly modify both the electronic structure and optical coefficients, including the linear, nonlinear, and third-order absorption behaviors. These coefficients are further examined as functions of photon energy and incident optical field intensity, exhibiting characteristics similar to those observed in quantum wells. Notably, the enhanced absorption within the visible and infrared regions highlights the strong potential of such quantum dots for advanced optoelectronic devices, particularly high-efficiency photodetectors, lasers, and solar energy conversion systems.
In this paper, a novel perovskite solar cell (PSC) structure incorporating a single-walled carbon nanotube (SWCNT) layer as a secondary electron transport layer (ETL) between the primary ETL and the top electrode is proposed and simulated. The electrical and optical effects of this additional layer on the PSC performance were investigated. Furthermore, the influence of nanotube chirality and the optimization of the SWCNT layer thickness were analyzed to enhance solar cell efficiency. Simulation results show that the incorporation of the SWCNT layer increases the conduction band slope in the perovskite layer, facilitating more efficient electron extraction and reducing recombination in this layer. Optically, the added layer reduces surface reflection and enhances light absorption within the perovskite layer thereby the short circuit current density (Jsc) is increased. As a result, the power conversion efficiency (PCE) of the proposed structure increased by 0.99% compared with the conventional PSC, reaching 20.39%.
In this research, a 2-D photonic crystal based hexagonal shaped system is presented. The designed device is consisted of 35*42 silicon rods (placed in air). Main functionality processes of the proposed biosensor were studied by considering photonic bandgap (PBG) and field distribution spectra. PBG and field diagrams could be obtained by using plane wave expansion (PWE) and finite-difference-time-domain (FDTD) numerical techniques. The designed system could be used for prognosis of cholesterol and creatinine levels in blood (these biological elements are introduced through their refractive indices). At defined wavelengths, incident signal could be transferred along the system and would reach outputs 1 or 2. Output1 could be applied for prognosis of cholesterol concentrations with quality factor (Q): (55.2 – 66.4), sensitivity (S): 1204.7nm/RIU, detection limit (DL): (0.0021–0.0031) RIU and figure of merit (FOM): (48.18–54.6) RIU-1. Output2 would be used for detection of creatinine with (Q): (175.7–195.5), (S): 1957.3nm/RIU, (DL): (4.8e-4 –5.2e-4) RIU and (FOM): (184.8–205.9) RIU-1. Based on the results, proposed device (biosensor) would aid physicians in diagnosis of various serious diseases.
