A Numerical Study of the Impact Ionization Coefficient Approximation Model of 2-D Lateral Power Devices

2021 ◽  
Author(s):  
Haidong Wang ◽  
Yufeng Guo ◽  
Jun Zhang ◽  
Maolin Zhang ◽  
Jing Chen
Keyword(s):  
Impact Ionization ◽  
Numerical Study ◽  
Ionization Coefficient ◽  
Approximation Model ◽  
Power Devices ◽  
The Impact

Modeling of a Breakdown Voltage in GaN Rectifiers and SiC Rectifiers

2001 ◽  
Vol 680 ◽  
Author(s):  
You-Sang Lee ◽  
Min-Koo Han ◽  
Yearn-Ik Choi
Keyword(s):  
Breakdown Voltage ◽  
Epitaxial Layer ◽  
Doping Concentration ◽  
Impact Ionization ◽  
Accurate Approximation ◽  
Ionization Coefficient ◽  
Zinc Blende ◽  
The Impact

ABSTRACTThe breakdown voltage of wurtzite and zinc-blende GaN rectifiers as function of a doping concentration and the width of epitaxial layer were successfully modeled in the reach-through case. The breakdown voltage was derived by the impact ionization integral employing the effective impact ionization coefficient and an accurate approximation. Our model shows that the breakdown voltage of wurtzite GaN rectifier was larger than those of zinc-blende GaN rectifier and SiC rectifiers including 4H-SiC and 6H-SiC in the condition that both the thickness and doping concentration of epitaxial layer are identical.

The Closed-Form Solutions For The Breakdown Voltages Of 6H-SiC Reachthrough Diodes

1998 ◽  
Vol 512 ◽  
Author(s):  
You-Sang Lee ◽  
D.-S. Byeon ◽  
Y.-I. Choi ◽  
I.-Y. Park ◽  
Min-Koo Han
Keyword(s):  
Closed Form ◽  
Breakdown Voltage ◽  
Epitaxial Layer ◽  
Doping Concentration ◽  
Impact Ionization ◽  
Analytic Solutions ◽  
Ionization Coefficient ◽  
Closed Form Solutions ◽  
The Impact ◽  
Effective Ionization

ABSTRACTThe closed-form analytic solutions for the breakdown voltage of 6H-SiC RTD, reachthrough diode, having the structure of p+-n-n+, are successfully derived by solving the impact ionization integral using effective ionization coefficient in the reachthrough condition. In the region of the lowly doped epitaxial layer, the breakdown voltages of 6H-SiC RTD nearly constant with the increased doping concentration. Also the breakdown voltages of 6H-SiC RTD decrease, in the region of the highly doped epitaxial layer, which coincides with Baliga'seq. [1].

Impact ionization threshold energy of trigonal selenium: An ab initio study

2013 ◽  
Vol 91 (6) ◽  
pp. 483-485 ◽  
Author(s):  
A. Darbandi ◽  
O. Rubel
Keyword(s):  
Impact Ionization ◽  
Threshold Energy ◽  
Charge Carriers ◽  
Ionization Threshold ◽  
Ab Initio Study ◽  
Ionization Coefficient ◽  
Semiconducting Material ◽  
Band Dispersion ◽  
Crude Approximation ◽  
The Impact

Impact ionization coefficient is a critical parameter that determines the multiplication gain in avalanche photodiodes. The impact ionization coefficient is closely related to the ionization threshold, Eth, which is determined by the band dispersion of the semiconducting material used in detectors. The ionization threshold energy is commonly calculated based on a parabolic band assumption, which provides only a crude approximation. Here we present a first principle study of the ionization threshold energy through an analysis of the electronic structure of trigonal selenium. It is shown that the excess energy of primary charge carriers required to initiate the impact ionization in trigonal selenium can be as low as the band gap, Eg, which is a sharp contrast to the parabolic band approximation that implies Eth = 3/2Eg. Such a low Eth value is a favourable factor for impact ionization.

Low-voltage Avalanche Breakdown in AlGaN Multi-quantum Wells

2006 ◽  
Vol 955 ◽  
Author(s):  
Shengkun Zhang ◽  
X. Zhou ◽  
Wubao Wang ◽  
R. R. Alfano ◽  
A. M. Dabiran ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Electric Fields ◽  
Impact Ionization ◽  
Low Voltage ◽  
Defect Density ◽  
Control Sample ◽  
Avalanche Breakdown ◽  
Ionization Coefficient ◽  
The Impact ◽  
Injection Modes

ABSTRACTIn this work, electro-luminescence (EL) of a AlGaN p-i-n diode have been investigated in both avalanche and injection modes. The active i-region of the diode consists of Al0.1Ga0.9N/Al0.15Ga0.85N MQWs. Strong interband luminescence from the Al0.1Ga0.9N active layers was observed when operating the device in both avalanche and injection modes. The threshold voltage for avalanche breakdown is as low as 9 V. This indicates that the impact ionization coefficient of electrons is greatly enhanced in these Al0.1Ga0.9N/Al0.15Ga0.85N MQWs comparing to AlGaN bulk materials. Polarization-induced electric fields in the Al0.1Ga0.9N well layers are believed to be responsible for the enhancement of the ionization coefficient. In a control sample that has higher defect density, the electroluminescence was dominated by long-wavelength emissions, which results from impact ionizations of the defect levels.

The impact ionization coefficient in dielectric materials revisited

2011 ◽  
Author(s):  
C. Karras ◽  
Z. Sun ◽  
D. N. Nguyen ◽  
L. A. Emmert ◽  
W. Rudolph
Keyword(s):  
Impact Ionization ◽  
Dielectric Materials ◽  
Ionization Coefficient ◽  
The Impact

Observation and Analysis of a Non-Uniform Avalanche Phenomenon in 4H-SiC 4°-Off (0001) p-n Diodes Terminated with a Floating-Field Ring

2015 ◽  
Vol 821-823 ◽  
pp. 640-643 ◽  
Author(s):  
Kazuhiro Mochizuki ◽  
Hiroyuki Okino ◽  
Hiroyuki Matsushima ◽  
Yoshiaki Toyota
Keyword(s):  
Opposite Direction ◽  
Impact Ionization ◽  
Two Dimensional ◽  
Ionization Coefficient ◽  
Dry Oxidation ◽  
Aluminum Implantation ◽  
Dimensional Simulation ◽  
The Impact

4H-SiC (0001) p-n diodes terminated with a floating-field ring were found to emit light at breakdown in the opposite direction to that of substrate misorientation when the diodes were fabricated by aluminum implantation and dry-oxidation passivation. Two-dimensional simulation revealed that such non-uniform breakdown was mainly attributable to the asymmetric lateral straggling of implanted aluminum acceptors, rather than the anisotropic nature of the impact ionization coefficient.

scholarly journals Model of thermal buoyancy in cavity-ventilated roof constructions

2021 ◽  
pp. 174425912098418
Author(s):  
Toivo Säwén ◽  
Martina Stockhaus ◽  
Carl-Eric Hagentoft ◽  
Nora Schjøth Bunkholt ◽  
Paula Wahlgren
Keyword(s):  
Analytical Model ◽  
Flow Rate ◽  
Numerical Study ◽  
Air Flow ◽  
Wind Pressure ◽  
Air Flow Rate ◽  
Test Set ◽  
Air Cavity ◽  
Thermal Buoyancy ◽  
The Impact

Timber roof constructions are commonly ventilated through an air cavity beneath the roof sheathing in order to remove heat and moisture from the construction. The driving forces for this ventilation are wind pressure and thermal buoyancy. The wind driven ventilation has been studied extensively, while models for predicting buoyant flow are less developed. In the present study, a novel analytical model is presented to predict the air flow caused by thermal buoyancy in a ventilated roof construction. The model provides means to calculate the cavity Rayleigh number for the roof construction, which is then correlated with the air flow rate. The model predictions are compared to the results of an experimental and a numerical study examining the effect of different cavity designs and inclinations on the air flow rate in a ventilated roof subjected to varying heat loads. Over 80 different test set-ups, the analytical model was found to replicate both experimental and numerical results within an acceptable margin. The effect of an increased total roof height, air cavity height and solar heat load for a given construction is an increased air flow rate through the air cavity. On average, the analytical model predicts a 3% higher air flow rate than found in the numerical study, and a 20% lower air flow rate than found in the experimental study, for comparable test set-ups. The model provided can be used to predict the air flow rate in cavities of varying design, and to quantify the impact of suggested roof design changes. The result can be used as a basis for estimating the moisture safety of a roof construction.

scholarly journals Numerical Simulation of the Impact of the Heat Source Position on Melting of a Nano-Enhanced Phase Change Material

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1425
Author(s):  
Tarek Bouzennada ◽  
Farid Mechighel ◽  
Kaouther Ghachem ◽  
Lioua Kolsi
Keyword(s):  
Heat Transfer ◽  
Phase Change ◽  
Phase Change Material ◽  
Numerical Study ◽  
Melting Rate ◽  
Heat Transfer Fluid ◽  
Commercial Code ◽  
Tube Position ◽  
The Impact ◽  
Change Material

A 2D-symmetric numerical study of a new design of Nano-Enhanced Phase change material (NEPCM)-filled enclosure is presented in this paper. The enclosure is equipped with an inner tube allowing the circulation of the heat transfer fluid (HTF); n-Octadecane is chosen as phase change material (PCM). Comsol-Multiphysics commercial code was used to solve the governing equations. This study has been performed to examine the heat distribution and melting rate under the influence of the inner-tube position and the concentration of the nanoparticles dispersed in the PCM. The inner tube was located at three different vertical positions and the nanoparticle concentration was varied from 0 to 0.06. The results revealed that both heat transfer/melting rates are improved when the inner tube is located at the bottom region of the enclosure and by increasing the concentration of the nanoparticles. The addition of the nanoparticles enhances the heat transfer due to the considerable increase in conductivity. On the other hand, by placing the tube in the bottom area of the enclosure, the liquid PCM gets a wider space, allowing the intensification of the natural convection.

OPTIMAL REINSURANCE FROM THE VIEWPOINTS OF BOTH AN INSURER AND A REINSURER UNDER THE CVAR RISK MEASURE AND VAJDA CONDITION

2021 ◽  
pp. 1-29
Author(s):  
Yanhong Chen
Keyword(s):  
Loss Function ◽  
Value At Risk ◽  
Numerical Study ◽  
Risk Measure ◽  
Convex Combination ◽  
Weighting Factor ◽  
Loss Functions ◽  
Conditional Value At Risk ◽  
Optimal Reinsurance ◽  
The Impact

ABSTRACT In this paper, we study the optimal reinsurance contracts that minimize the convex combination of the Conditional Value-at-Risk (CVaR) of the insurer’s loss and the reinsurer’s loss over the class of ceded loss functions such that the retained loss function is increasing and the ceded loss function satisfies Vajda condition. Among a general class of reinsurance premium principles that satisfy the properties of risk loading and convex order preserving, the optimal solutions are obtained. Our results show that the optimal ceded loss functions are in the form of five interconnected segments for general reinsurance premium principles, and they can be further simplified to four interconnected segments if more properties are added to reinsurance premium principles. Finally, we derive optimal parameters for the expected value premium principle and give a numerical study to analyze the impact of the weighting factor on the optimal reinsurance.

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