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排序方式: 共有143条查询结果,搜索用时 15 毫秒
1.
Chandramouli V. Maziar C.M. Campbell J.C. 《Electron Devices, IEEE Transactions on》1994,41(5):648-654
We have studied the effect of the thickness of the multiplication region on the noise performance characteristics of avalanche photodiodes (APD's). Our simulation results are based on a full band Monte Carlo model with anisotropic threshold energies for impact ionization. Simulation results suggest that the well known McIntyre expression for the excess noise factor is not directly applicable for devices with a very thin multiplication region. Since the number of ionization events is drastically reduced when the multiplication layer is very thin, the “ionization coefficient” is not a good physical parameter to characterize the process. Instead “effective quantum yield,” which is a measure of the total electron-hole pair generation in the device, is a more appropriate parameter to consider. We also show that for the device structure considered here, modeling the excess noise factor using a “discrete Bernoulli trial” model as opposed to the conventional “continuum theory” produces closer agreement to experimental measurements. Our results reinforce the understanding that impact ionization is a strong function of carrier energy and the use of simplified field-dependent models to characterize this high energy process fails to accurately model this phenomenon 相似文献
2.
McKeon J.B. Chindalore G. Hareland S.A. Shih W.-K. Wang C. Tasch A.F. Jr. Maziar C.M. 《Electron Device Letters, IEEE》1997,18(5):200-202
This letter presents for the first time, the experimentally determined majority carrier mobilities in the accumulation layer of a MOSFET for both p-type and n-type channel doping for a wide range of doping concentrations. The measured carrier mobility is observed to follow a universal behavior at high transverse fields, similar to that observed for minority carriers in MOS inversion layers. At the higher doping levels, the effective mobility for majority carriers at low to moderate transverse fields is found to be very close to the bulk mobility. This is believed to be due to carrier screening of the ionized impurity scattering which dominates at the higher doping concentrations 相似文献
3.
Noei Maziar Luckner Paul Linn Tobias Jungemann Christoph 《Journal of Computational Electronics》2022,21(1):153-168
Journal of Computational Electronics - We discuss the numerical aspects of the Boltzmann transport equation (BE) for electrons in semiconductor devices, which is stabilized by Godunov’s... 相似文献
4.
In the present article, as a first endeavor, the wave propagation in functionally graded nanocomposites reinforced with carbon nanotubes is investigated on the basis of second-order shear deformation theory. Four different types of functionally graded nanocomposites are presented. An analytical method is used to find the circular frequencies and phase velocities. To show the accuracy of the present methodology, our results for the free vibration are compared with the results of functionally graded plates available in the literature. The influences of different parameters are also investigated on the circular frequencies and phase velocities. 相似文献
5.
Maziar Gholami Korzani Sergio A. Galindo-Torres Alexander Scheuermann David J. Williams 《水科学与水工程》2017,10(2):143-153
Simulations of two-dimensional (2D) flow past a circular cylinder with the smoothed particle hydrodynamics (SPH) method were conducted in order to accurately determine the drag coefficient. The fluid was modeled as a viscous liquid with weak compressibility. Boundary conditions, such as a no-slip solid wall, inflow and outflow, and periodic boundaries, were employed to resemble the physical problem. A sensitivity analysis, which has been rarely addressed in previous studies, was conducted on several SPH parameters. Hence, the effects of distinct parameters, such as the kernel choices and the domain dimensions, were investigated with the goal of obtaining highly accurate results. A range of Reynolds numbers (1–500) was simulated, and the results were compared with existing experimental data. It was observed that the domain dimensions and the resolution of SPH particles, in comparison to the obstacle size, affected the obtained drag coefficient significantly. Other parameters, such as the background pressure, influenced the transient condition, but did not influence the steady state at which the drag coefficient was determined. 相似文献
6.
In this research, polyester fabrics were treated with three concentrations (10, 20 and 30 g/L) of macro- and microemulsions
of silicones in water at 30 °C by the padding method. The treated fabrics were then dried/cured at 130 °C for 40 s. Some of
the physical and chemical properties of the samples are discussed. The drapeability of treated samples was lower and found
to depend on the silicone particle size. Moisture absorbency of treated samples was also lower. Colorimetric properties of
softener treated fabrics were evaluated with a reflectance spectrophotometer. Scanning electron microscope (SEM) examinations
showed an aggregation of silicone particles on the fiber surface.
相似文献
Mazeyar ParvinzadehEmail: |
7.
Strong glass-ceramics (GCs) have been envisaged and widely researched for various applications, including large architectural panels, ballistic impact protection, bioactive medical implants, and odontological prostheses. Here, we report on the development and characterization of a novel hard, strong and tough enstatite-zirconia (MgSiO3-ZrO2) glass-ceramic derived from a 51SiO2–35MgO–6Na2O–4ZrO2–4TiO2 (mol%) glass. The best GC was developed by treating glass samples for nucleation at 700°C for 12 hours, followed by crystal growth at 1090°C for 3 minutes. It was characterized by X-ray fluorescence (XRF), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM), and contained plate-like enstatite, zirconia, and Ti-containing crystals. We investigated the nucleating ability of ZrO2 and TiO2 in inducing internal nucleation. In the early stage of crystallization, enstatite spherulites were observed, which were precipitated by heterogeneous nucleation on previously nucleated ZrO2 nano-crystals. At more advanced stages, at high temperatures, they transformed into plate-like crystals. The ball-on-three-balls strength, elastic modulus, and Vickers micro-hardness of the GC are 323 ± 26 MPa, 146 ± 13 GPa, and 6.9 ± 0.1 GPa (load = 5N), respectively. The indentation (KC), single-edge notched beam bending (KIC), and crack tip (Ktip) fracture toughness are 2.8 ± 0.6 MP.m0.5, 2.2 ± 0.3 MP.m0.5, 1.9 ± 0.3 MP.m0.5, respectively. The crack propagation profile after a controlled Vickers indentation was quite intricate. The enstatite and zirconia crystals enhanced crack deflection, bridging and branching, hindering crack propagation. According to the ISO 6872 for dental materials, the chemical solubility of our GC is 80 ± 5 μg/cm2. Due to this positive combination of high strength, toughness, hardness, and chemical durability, this new glass-ceramic is envisioned as a candidate for several applications and could be further developed for memory disc substrates, architectural cladding and tiles, ceramic glazes, and dental materials. 相似文献
8.
Chindalore G.L. McKeon J.B. Mudanai S. Hareland S.A. Shih W.-K. Wang C. Tasch A.F. Jr. Maziar C.M. 《Electron Devices, IEEE Transactions on》1998,45(2):502-511
For the first time, experimental results are presented for electron and hole mobilities in the electron and hole accumulation layers of a MOSFET for a wide range of doping concentrations. Also presented is an improved methodology that has been developed in order to enable more accurate extraction of the accumulation layer mobility. The measured accumulation layer mobility for both electrons and holes is observed to follow a universal behavior at high transverse electric fields, similar to that observed for minority carriers in MOS inversion layers. At low to moderate transverse fields, the effective carrier mobility values are greater than the bulk mobility values for the highest doping levels. This is due to screening by accumulated carriers of the ionized impurity scattering by accumulated carriers, which dominates at higher doping concentrations. For lower doping levels, surface phonon scattering is dominant at low to moderate transverse fields so that the carrier mobility is below the bulk mobility value 相似文献
9.
M.M. Sarafraz Mehdi Jafarian Maziar Arjomandi Graham J. Nathan 《International Journal of Hydrogen Energy》2017,42(26):16396-16407
The relative performance of different potential liquid oxygen carriers within a novel system that can be configured for either chemical looping gasification or combustion is assessed. The parameters considered here are the melting temperature, the Gibbs free energy, reaction enthalpy, exergy and energy flows, syngas quality and temperature difference between the two reactors. Results show that lead, copper and antimony oxides are meritorious candidates for the proposed systems. Antimony oxide was found to offer strong potential for high quality syngas production because it has a reasonable oxygen mass ratio for gasification. A sufficiently low operating temperature to be compatible with concentrated solar thermal energy and a propensity to generate methane. In contrast, copper and lead oxides offer greater potential for liquid chemical looping combustion because they have higher oxygen mass ratio and a higher operating temperature, which enables better efficiency from a power plant. For all three metal oxides, the production of methane via the undesirable methanation reaction is less than 2% of the product gasses for all operating temperatures and an order of magnitude lower for lead. 相似文献
10.
Mazeyar Parvinzadeh Naser Memari Mohammad Shaver Bashir Katozian Saeed Ahmadi Issa Ziadi 《Journal of surfactants and detergents》2010,13(2):135-141
In recent years, the textile industry has been forced to develop new technologies to reduce energy and water consumption.
The use of ultrasound in textile wet processing is one solution to this problem. The aim of this work was to investigate the
effects of ultrasonic energy on the processing of cotton with a cationic softener. For this purpose, cotton fabric was treated
with a fatty acid amide derivative cationic softener in water using ultrasonic energy during treatment. The physical properties
of the fabrics treated under different conditions are discussed. The results show that the treatment of fabrics with softeners
in an ultrasound bath is more effective compared to conventional methods and that it enhances the physical properties of the
cotton. 相似文献