Semiconductor Model Research Articles

High-Efficiency e-Powertrain Topology by Integrating Open-End Winding and Winding Changeover for Improving Fuel Economy of Electric Vehicles

The fuel economy of electric vehicles (EVs) is an important factor in determining the competitiveness of EVs. Since the fuel economy is affected by the efficiency of an e-powertrain composed of a motor and inverter, it is necessary to select a high-efficiency topology for the e-powertrain. In this paper, a novel topology of e-powertrains to improve the fuel economy of EVs is proposed. The proposed topology aims to improve the system efficiency by integrating open-end winding (OEW) and winding changeover (WC). The proposed OEW-PMSM with WC enables to drive a permanent magnet synchronous motor (PMSM) in four different modes. Each mode can increase inverter efficiency and motor efficiency by changing motor parameters and maximum modulation index. In this paper, the system efficiency of the proposed topology was evaluated using electromagnetic finite element analysis and a loss model of power semiconductors. In addition, the vehicle simulations were performed to evaluate the fuel economy of the proposed topology, thereby proving the superiority of the proposed topology compared with the conventional PMSM.

Relaxation Time Limits of Subsonic Steady States for Multidimensional Hydrodynamic Model of Semiconductors

Relaxation Time Limits of Subsonic Steady States for Multidimensional Hydrodynamic Model of Semiconductors

An Enhanced LPRAFF with Tri-State Inverter Embedded Non-Clock Gating via the CT-GWO Algorithm

Since a long time ago, it has been understood how radiation affects digital circuits, particularly those using the Complementary Metal Oxide Semiconductor (CMOS) model. Total Ionisation Dose (TID) and Single Event Effects (SEE) are the two most significant radiation effects. Depending on the gate input count, the complexity of the circuit will rise, which will worsen the radiation and raise the cumulative dose levels. The incremental dose level affects the circuit parameter failure, which affects how well the logic design functions. Many authors concentrate on minimising the effects of radiation while preventing function loss, but these extra efforts use excess energy. To improve the efficiency of the Low Power Radiation Aware (LPRA) circuit, this paper introduces optimisation concepts in a Flip Flop (FF) architecture named Chaos Theory-based Grey Wolf Optimised FF (CT-GWOFF). First, compute each component's radiation response using a physics-based modelling strategy. To minimise undesirable latches and disable the inverter chain when the input data remain constant, a tri-state inverter, incorporating a non-clocked gating mechanism, is provided. This prevents repeated transitions of delayed clock signals. Moreover, the proposed model is implemented in FFs for simulation purposes, making it more cognizant of radiation effects and power consumption. Using the HSPICE tool, the performance of the suggested circuit design is evaluated at the 16 nm CMOS Predictive Technology Model (PTM).

First-principles quantum Monte Carlo study of charge-carrier mobility in organic molecular semiconductors

We present a first-principles numerical study of charge transport in a realistic two-dimensional tight-binding model of organic molecular semiconductors. We use the hybrid Monte Carlo (HMC) algorithm to simulate the full quantum dynamics of phonons and either single or multiple charge carriers without any tunable parameters. We introduce a number of algorithmic improvements, including efficient Metropolis updates for phonon fields based on analytical insights, which lead to negligible autocorrelation times and allow sub-per-mille precisions to be reached at a low computational cost of O(1) CPU hours. Our simulations produce charge-mobility estimates that are in good agreement with experiments and that also justify the phenomenological transient localization approach. Published by the American Physical Society 2024

The uniqueness of steady sonic–subsonic solution to hydrodynamic model for semiconductors

In this paper, we study the uniqueness of the stationary sonic–subsonic solution to the isentropic hydrodynamic model of semiconductors with sonic boundary. We provide a new method to improve the proof of the uniqueness of the steady-state sonic–subsonic solution, even for the general isentropic case. In detail, we apply the exponential variation method combining a series of modifications with respect to the degeneracy of electrons at the boundary. The proposed method in the present paper is much simpler and perfecter than the existing methods.

Interplay of Phonon Directionality and Emission Polarization in Two-Dimensional Layered Metal Halide Perovskites.

ConspectusLayered metal halide perovskites represent a natural quantum well system for charge carriers that provides rich physics, and the organic encapsulation of the inorganic metal halide layers not only increases their stability in devices but also provides an immense freedom to design their functionality. Intriguingly, these organic moieties strongly impact the optical, electrical, and mechanical properties, not only through their dielectric, elastic, and chemical properties but also because of induced mechanical distortions in the inorganic lattice. This tunability makes two-dimensional layered perovskites (2DLPs) highly attractive as light emitters. Common consensus is that exciton-phonon coupling plays an important role in radiative recombination. For bulk and some two-dimensional (2D) materials, the band edge emission broadening can be described by the classic models for polar inorganic semiconductors, while for the temperature dependence of the self-trapped exciton emission, an analysis developed for color centers has been successfully applied. For many 2DLPs these approaches do not work because of the complexity of their vibrational spectra. However, their emission is still strongly determined by phonons, and therefore, an adequate understanding of the electron-phonon coupling needs to be developed.With polarized and angle-resolved Raman spectroscopy studies on single 2DLP flakes based on different ammonium molecules as organic cations, in 2020 we revealed very rich phonon spectra in the low-frequency regime. Although the phonon bands at low frequency can generally be attributed to the vibrations of the inorganic lattice, we found very different responses by only changing the type of organic cations. In addition, the intensity of the different phonon modes depended strongly on the angle of the linearly polarized excitation beam with respect to the in-plane axes of the octahedron lattice. In 2022, we mapped this angular dependence of the phonon modes, which allowed identification of the directionality of the different lattice vibrations. By correlating the phonon spectra with the temperature-dependent emission for a set of 2DLPs that featured very different self-trapped exciton (STE) emission, we demonstrated that the exciton relaxation cannot be related to coupling with a single (longitudinal-optical) phonon band and that several phonon bands should be involved in the emission process. To gain insights into the exciton-phonon coupling effects on the band edge emission, we performed both angle-resolved polarized emission and Raman spectroscopy on single 2D lead iodide perovskite microcrystals. These experiments revealed the impact of the organic cations on the linear polarization of the emission and corroborated that multiple phonon bands should be involved in the radiative recombination process. Analysis of the temperature-dependent line width broadening of the band edge emission showed that for many systems, the behavior cannot be described by assuming the involvement of only one phonon mode in the electron-phonon coupling process. Our studies revealed a wealth of highly directional low-frequency phonons in 2DLPs from which several bands are involved in the emission process, which leads to diverse optical and vibrational properties depending on the type of organic cation in the material.

Development of S-domain experimental correlation thermal control model and rapid enumeration PID tuning method for uncooled Laser chip module

Uncooled semiconductor lasers are sensitive to ambient temperature variation which makes the PID thermal control for the uncooled semiconductor is complicated. In this work, a kind of enumeration PID tuning method based on S-domain experimental correlation thermal control model for the uncooled semiconductor lasers is introduced. Numeric validation and enumeration PID tuning of S-domain experimental correlation model for uncooled semiconductor are conducted. Results shows that the control accuracy prediction result of the S-domain experimental correlation model has a deviation of 3.6% in contrast with CAE simulation result. The PID tunning speed of rapid enumeration S-domain experimental correlation method is 17,000 times that of CAE method.

Advances in CMOS Image Sensors and Transistors Leveraging Stochastic Nanomagnets: A Comprehensive Review

Accurate modeling and assessment of complex Complementary Metal-Oxide Semiconductor (CMOS) imaging sensors and transistors, in conjunction with randomized nanomagnets for distributed computation in radiated environments, are crucial for the development of robust electronic systems. The effectiveness and resilience of these intricate parts to radiation exposure is the subject of this study, which is becoming more and more important in applications including space missions, power plants, and high-altitude flying. To take into account the interaction between CMOS technology and the unpredictable behavior of nanomagnets, a comprehensive durability modeling technique is required. The methodology that has been suggested evaluates the susceptibility of image detectors and transistors to malfunctions caused by radiation, such as dislocation damage, single-event upsets (SEUs), and impacts of total ionizing dose (TID). The impact of radiation on the power characteristics and operational dependability of these components is investigated using state-of-the-art modeling tools and experimental data. The findings suggest that random nanomagnets can improve distributed computing devices' resistance to radiation-induced failures. Through the provision of insights into reliability challenges and solutions for enhanced CMOS image sensors and transistors, this work advances the field of radiation-tolerant technologies. Future electronic device developers will find the suggested reliability modeling and evaluation methodology to be a useful resource for creating reliable devices that can resist harsh radioactive environments. Keywords— Reliability Modeling; CMOS Image Sensors; Radiation Environment; Advanced Technology Node; Transistor Structures; Stochastic Nanomagnets; Heterogeneous Computing; Probabilistic Inference

Energy transfer, conversion and mechanical regulation in graded piezoelectric semiconductor bipolar junction transistor

While the effective regulation of carrier redistribution in piezoelectric semiconductor devices by mechanical loads through piezoelectric polarized electric fields is well-studied, there is a scarcity of reported research on the influence of energy transfer and conversion characteristics in a non-thermal equilibrium state of these devices. This paper establishes a nonlinear multi-field coupling model for piezoelectric semiconductor graded bipolar junction transistor (PS-GBJT) and proposes a corresponding multi-gradient iterative algorithm. We regard the product of current and built-in electric field as the work done by electric field force on carriers. By incorporating the energy absorbed/released during carrier recombination/generation process, we observe that non-equilibrium carriers act as a medium that facilitates energy conversion between these two mechanisms. Additionally, the non-uniformly distributed doping extends the influence of space charge region throughout entire transistor. In terms of external input electrical energy, the emitter, base, and collector regions play roles of input energy, transfer energy, and output energy, respectively. The study concludes by demonstrating the regulation of energy transfer or conversion efficiency in emitter, base, and collector regions through mechanical loads, thereby altering the heating behavior of entire GBJT and reshaping its energy transfer path. This leads to the significant finding that distinct energy transfer paths fundamentally define the various operational states of GBJT. The novel insights gained from this research hold reference value for thermal design and energy management of electronic devices.

Harnessing Persistent Photocurrent in a 2D Semiconductor-Polymer Hybrid Structure: Electron Trapping and Fermi Level Modulation for Optoelectronic Memory.

Recently, 2D semiconductor-based optoelectronic memory has been explored to overcome the limitations of conventional von Neumann architectures by integrating optical sensing and data storage into one device. Persistent photocurrent (PPC), essential for optoelectronic memory, originates from charge carrier trapping according to the Shockley-Read-Hall (SRH) model in 2D semiconductors. The quasi-Fermi level position influences the activation of charge-trapping sites. However, the correlation between quasi-Fermi level modulations and PPC in 2D semiconductors has not been extensively studied. In this study, we demonstrate optoelectronic memory based on a 2D semiconductor-polymer hybrid structure and confirm that the underlying mechanism is charge trapping, as the SRH model explains. Under light illumination, electrons transfer from polyvinylpyrrolidone to p-type tungsten diselenide, resulting in high-level injection and majority carrier-type transitions. The quasi-Fermi level shifts upward with increasing temperature, improving PPC and enabling optoelectronic memory at 433 K. Our findings offer valuable insights into optimizing 2D semiconductor-based optoelectronic memory.

Numerical Diagnostics of Solution Blow-Up in a Thermoelectric Semiconductor Model

Numerical Diagnostics of Solution Blow-Up in a Thermoelectric Semiconductor Model

Pulsed Laser-Bleaching Semiconductor and Photodetector.

Pulsed lasers alter the optical properties of semiconductors and affect the photoelectric function of the photodetectors significantly, resulting in transient changes known as bleaching. Bleaching has a profound impact on the control and interference of photodetector applications. Experiments using pump-probe techniques have made significant contributions to understanding ultrafast carrier dynamics. However, there are few theoretical studies to the best of our knowledge. Here, carrier dynamic models for semiconductors and photodetectors are established, respectively, employing the rectified carrier drift-diffusion model. The pulsed laser bleaching effect on seven types of semiconductors and photodetectors from visible to long-wave infrared is demonstrated. Additionally, a continuous bleaching method is provided, and the finite-difference time-domain (FDTD) method is used to solve carrier dynamic theory models. Laser parameters for continuous bleaching of semiconductors and photodetectors are calculated. The proposed bleaching model and achieved laser parameters for continuous bleaching are essential for several applications using semiconductor devices, such as infrared detection, biological imaging, and sensing.

Global existence of solutions for the drift–diffusion system with large initial data in [formula omitted] ([formula omitted])

In this paper, we study the Cauchy problem of the drift–diffusion system arising from semiconductor model. We prove that if a certain nonlinear function of the initial data is small enough, in a Besov type space, then there is a global solution to this drift–diffusion system. We also provide an example of initial data satisfying that nonlinear smallness condition, but whose norm be chosen arbitrarily large in Ḃ∞,∞−2(Rd).

Continuous Time Simulation and System-Level Model of a MVDC Distribution Grid Including SST and MMC-Based AFE

Medium-voltage DC (MVDC) technology has gained increasing attention in recent years. Power electronics devices dominate these grids. Accurate simulation of such a grid, with detailed models of switching semiconductors, can quickly became very time-consuming, according to the number of connected devices to be simulated. A simulation approach based on interactions on a continuous time model can be very interesting, especially for developing a system-level control model of such a modern MVDC distribution grid. The aim of this paper is to present all the steps required for obtaining a continuous time modelling of a +/−10 kV MVDC grid case study, including a solid-state transformer (SST)- and modular multilevel converter (MMC)-based active front end (AFE). An additional aim of this paper is to supply educational content about the use of the continuous time simulation approach, thanks to a detailed description of the various devices modelled into the presented MVDC grid. The results of a certain number of simulation scenarios are eventually presented.

Relaxation Time Limits of Subsonic Steady States for Hydrodynamic Model of Semiconductors with Sonic or Nonsonic Boundary

Relaxation Time Limits of Subsonic Steady States for Hydrodynamic Model of Semiconductors with Sonic or Nonsonic Boundary

An Asymptotic Preserving Discontinuous Galerkin Method for a Linear Boltzmann Semiconductor Model

An Asymptotic Preserving Discontinuous Galerkin Method for a Linear Boltzmann Semiconductor Model

High-purity germanium semiconductor modeling in the detector response function toolkit

We have extended the detector response function toolkit (DRiFT) to provide modeling capabilities of semiconductor sensors. DRiFT provides realistic nuclear instrumentation response by post-processing Monte-Carlo N-particle (MCNP®) radiation transport outputs. MCNP® is capable of modeling radiation transport in complex environments, but has limited detector physics and readout electronics modeling capabilities. Semiconductor detector response can be calculated with a high-fidelity for a flexible range of environments by utilizing MCNP® to simulate radiation interactions inside of detector volumes, and then using DRiFT to model charge transport and signal formation in the semiconductor, as well as the readout electronics. DRiFT models charge transport in the semiconductor, the preamplifier, shaping amplifier, pulse pile-up, and electronic noise to generate detector response. The semiconductor application in DRiFT can model a range of semiconductor materials, shapes, and sizes; and is demonstrated here for a large volume coaxial high-purity germanium (HPGe) detector. Here, we compare detector response functions of a coaxial HPGe detector with measurement of 60Co, 133Ba, and 137Cs at varying count rates, and we conduct a parameter study to demonstrate the effect of changing parameters in the DRiFT simulation. The HPGe detector response function shows excellent agreement with measurements of difference sources with varying dead times and count rates.

Asymptotic preserving methods for quasilinear hyperbolic systems with stiff relaxation: a review

Hyperbolic systems with stiff relaxation constitute a wide class of evolutionary partial differential equations which describe several physical phenomena, ranging from gas dynamics to kinetic theory, from semiconductor modeling to traffic flow. Peculiar features of such systems is the presence of a small parameter that determines the smallest time scale of the system. As such parameter vanishes, the system relaxes to a different one with a smaller number of equations, and sometime of a different mathematical nature. The numerical solution of such systems may present some challenges, in particular if one is interested in capturing all regimes with the same numerical method, including the one in which the small parameter vanishes (relaxed system). The design, analysis and application of numerical schemes which are robust enough to solve this class of systems for arbitrary value of the small parameter is the subject of the current paper. We start presenting different classes of hyperbolic systems with relaxation, illustrate the properties of implicit–explicit (IMEX) Runge–Kutta schemes which are adopted for the construction of efficient methods for the numerical solution of the systems, and then illustrate how to apply IMEX schemes for the construction of asymptotic preserving schemes, i.e. scheme which correctly capture the behavior of the systems even when the relaxation parameter vanishes.

Global solutions and relaxation limit to the Cauchy problem of a hydrodynamic model for semiconductors

In this paper, we study the Cauchy problem for the one-dimensional Euler-Poisson (or hydrodynamic) model for semiconductors, where the energy equation is replaced by a pressure-density relation. First, the existence of global entropy solutions is proved by using the vanishing artificial viscosity method, where, a special flux approximate is introduced to ensure the uniform boundedness of the electric field E and the a-priori L∞ estimate, 0<2δ≤ρε,δ≤M(t),|uε,δ|≤M(t), where M(t) could tend to infinity as the time t tends to infinity, on the viscosity-flux approximate solutions (ρε,δ,uε,δ); Second, the compensated compactness theory is applied to prove the pointwise convergence of (ρε,δ,uε,δ) as ε,δ go to zero, and that the limit (ρ(x,t),u(x,t)) is a global entropy solution; Third, a technique, to apply the maximum principle to the combination of the Riemann invariants and ∫−∞xρε,δ(x,t)−2δdx, deduces the uniform L∞ estimate, 0<2δ≤ρε,δ≤M,|uε,δ|≤M, independent of the time t and ε,δ; Finally, as a by-product, the known compactness framework [14,29] is applied to show the relaxation limit, as the relation time τ and ε,δ go to zero, for general pressure P(ρ).

The subsonic or sonic–subsonic solution of the electric potential driven problem to the HD model for semiconductors

This paper concerns the stationary subsonic or sonic–subsonic solution of the electric potential driven problem to the isentropic hydrodynamic model for semiconductors. We give a necessary and sufficient condition to ensure the existence of this kind of solution. Specifically, there exists a subsonic or sonic–subsonic solution to this problem if and only if 0≤ϕr≤ϕ̄, with the number ϕ̄=O1τ. Here, ϕr is the right side electric potential and τ is the relaxation time. Moreover, there is a number ϕ̃∈(0,ϕ̄] such that when ϕr=ϕ̃, there exists a sonic–subsonic solution. In this way, we show the influence of the relationship between the boundary value of the electric potential and the semiconductor effect on the existence of this kind of solution. Finally, we prove the uniqueness of subsonic solution by the energy method under the assumption that ϕr and ϕrτ are both small enough.