A Gate Breakdown Mechanism in Mesfets and HEMTs

1991 ◽  
Vol 241 ◽  
Author(s):  
R. J. Trew ◽  
T. A. Winslow ◽  
U. K. Mishra
Keyword(s):  
Experimental Data ◽  
Thermal Effects ◽  
Light Emission ◽  
Avalanche Breakdown ◽  
Gate Electrode ◽  
Gate Current ◽  
Versus Bias ◽  
Breakdown Mechanism ◽  
Assisted Tunneling ◽  
First Time

ABSTRACTA model for gate breakdown in MESFETs and HEMTs is proposed. The model is based upon a combination of thermally assisted tunneling and avalanche breakdown. When thermal effects are considered it is demonstrated that the model predicts increasing drain-source breakdown as the gate electrode is biased towards pinch-off, in agreement with experimental data. The model also predicts, for the first time, the gate current versus bias behavior observed in experimental data. The model is consistent with the various reports of breakdown and light emission phenomena reported in the literature.

Bulk Breakdown in AlGaN/GaN HFETs

1998 ◽  
Vol 512 ◽  
Author(s):  
G. Gradinaru ◽  
N. C. Kao ◽  
R. Gaska ◽  
J. Yang ◽  
Q. Chen ◽  
...  
Keyword(s):  
Light Emission ◽  
Large Range ◽  
Simultaneous Increase ◽  
Gate Current ◽  
Emission Signal ◽  
Multiplication Process ◽  
Breakdown Mechanism ◽  
Carrier Multiplication ◽  
Source Current

ABSTRACTA significant source current generated by a carrier multiplication process is observed at large drain voltages in the subthreshold regime, along with simultaneous increase of the gate current and light emission signal. Provided no on-surface premature breakdown takes place, a bulk channel avalanche breakdown process is proposed as the dominant breakdown mechanism for a large range of gate-to-source dc voltages. This process in the GaN channel is responsible for the excess source and drain currents, light emission, and excess gate current beyond its normal value measured in a gate-to-drain diode configuration. The role of the gate bias in controlling the channel vs. the gate breakdown mechanisms is described.

An expression for droplet evaporation incorporating thermal effects

2011 ◽  
Vol 667 ◽  
pp. 260-271 ◽  
Author(s):  
K. SEFIANE ◽  
R. BENNACER
Keyword(s):  
Experimental Data ◽  
Thermal Effects ◽  
Droplet Evaporation ◽  
Theoretical Expression ◽  
Dimensionless Number ◽  
Wide Range ◽  
Isothermal Diffusion ◽  
Rate Of Evaporation ◽  
First Time ◽  
Kinetics Of

We propose a general theoretical expression for sessile droplets' evaporation, incorporating thermal effects related to the thermal resistance of the substrate and liquid properties. We develop an expression which accounts for thermal effects associated with evaporative cooling; the latter leads to a reduction in the rate of evaporation, which is not accounted for in the current theories, i.e. ‘isothermal diffusion theories’. The threshold for transition to a regime in which thermal effects start to be significant is identified through a dimensionless number which includes substrate and liquid properties as well as the kinetics of evaporation. The proposed theory is validated against experimental data in a very wide range of conditions and for a variety of systems. The developed expression extends the domain of use of diffusion-based models for droplet evaporation and accurately describes some aspects of the phenomenon which, to the best of our knowledge, are highlighted for the first time.

LUMINESCENCE OF THE BLACK SEA MICROSCOPIC FUNGI CULTURES

2017 ◽  
Author(s):  
Olga Mashukova ◽  
Olga Mashukova ◽  
Yuriy Tokarev ◽  
Yuriy Tokarev ◽  
Nadejda Kopytina ◽  
...  
Keyword(s):  
Fresh Water ◽  
Black Sea ◽  
Ethyl Alcohol ◽  
Light Emission ◽  
Sea Water ◽  
Control Culture ◽  
Chemical Stimulation ◽  
The Black Sea ◽  
The Given ◽  
First Time

We studied for the first time luminescence characteristics of the some micromycetes, isolated from the bottom sediments of the Black sea from the 27 m depth. Luminescence parameters were registered at laboratory complex “Svet” using mechanical and chemical stimulations. Fungi cultures of genera Acremonium, Aspergillus, Penicillium were isolated on ChDA medium which served as control. Culture of Penicillium commune gave no light emission with any kind of stimulation. Culture of Acremonium sp. has shown luminescence in the blue – green field of spectrum. Using chemical stimulation by fresh water we registered signals with luminescence energy (to 3.24 ± 0.11)•108 quantum•cm2 and duration up to 4.42 s, which 3 times exceeded analogous magnitudes in a group, stimulated by sea water (p < 0.05). Under chemical stimulation by ethyl alcohol fungi culture luminescence was not observed. Culture of Aspergillus fumigatus possessed the most expressed properties of luminescence. Stimulation by fresh water culture emission with energy of (3.35 ± 0.11)•108 quantum•cm2 and duration up to 4.96 s. Action of ethyl alcohol to culture also stimulated signals, but intensity of light emission was 3–4 times lower than under mechanical stimulation. For sure the given studies will permit not only to evaluate contribution of marine fungi into general bioluminescence of the sea, but as well to determine places of accumulation of opportunistic species in the sea.

Simulation of Laminar Liquid Jets in Gaseous Crossflow Before the Onset of Primary Breakup

2011 ◽  
Author(s):  
C.-L. Ng ◽  
K. A. Sallam
Keyword(s):  
Experimental Data ◽  
Fuel Injection ◽  
Liquid Jets ◽  
Liquid Jet ◽  
Jet Breakup ◽  
Primary Breakup ◽  
Density Ratios ◽  
First Time ◽  
Two Sides ◽  
Reduced Pressures

The deformation of laminar liquid jets in gaseous crossflow before the onset of primary breakup is studied motivated by its application to fuel injection in jet afterburners and agricultural sprays, among others. Three crossflow Weber numbers that represent three different liquid jet breakup regimes; column, bag, and shear breakup regimes, were studied at large liquid/gas density ratios and small Ohnesorge numbers. In each case the liquid jet was simulated from the jet exit and ended before the location where the experimental data indicated the onset of breakup. The results show that in column and bag breakup, the reduced pressures along the sides of the jet cause the liquid to move to the sides of the jet and enhance the jet deformation. In shear breakup, the flattened upwind surface pushes the liquid towards the two sides of the jet and causing the gaseous crossflow to separate near the edges of the liquid jet thus preventing further deformation before the onset of breakup. It was also found out that in shear breakup regime, the liquid phase velocity inside the liquid jet was large enough to cause onset of ligament formation along the jet side, which was not the case in the column and bag breakup regimes. In bag breakup, downwind surface waves were observed to grow along the sides of the liquid jet triggered a complimentary experimental study that confirmed the existence of those waves for the first time.

Mesoscopic characterization of the optical property of antiphase boundaries in CuPt-ordered GaInP2

1999 ◽  
Vol 588 ◽  
Author(s):  
Y. Ohno ◽  
S. Takeda
Keyword(s):  
Optical Property ◽  
Light Emission ◽  
Polarized Light ◽  
Structural Data ◽  
Luminescence Spectra ◽  
Antiphase Boundaries ◽  
Transmission Electron ◽  
Tem Method ◽  
Low Dimensional ◽  
First Time

AbstractWe have developed an apparatus for polarized cathodoluminescence (CL) spectroscopy combined with transmission electron microscopy (TEM), that enables us to obtain simultaneously structural data in higher spatial resolution by TEM and polarized luminescence spectra by CL of the same microscopic area. The polarized-CL/TEM method is very useful to study the optical properties of low-dimensional microstructures in semiconducting materials. We have applied the method to examine the optical property of antiphase boundaries in CuPt-ordered GaInP2 and found, for the first time, the polarized light emission from the APBs whose habit planes are parallel to the (T11) and (1T0) atomic planes.

Dose-window dependence on Si crystal orientation in separation by implanted oxygen substrate formation

2004 ◽  
Vol 19 (12) ◽  
pp. 3607-3613 ◽  
Author(s):  
H. Iikawa ◽  
M. Nakao ◽  
K. Izumi
Keyword(s):  
Experimental Data ◽  
Numerical Analysis ◽  
Crystal Orientation ◽  
Oxygen Ion ◽  
The Difference ◽  
First Time ◽  
Good Agreement

Separation by implemented oxygen (SIMOX)(111) substrates have been formed by oxygen-ion (16O+) implantation into Si(111), showing that a so-called “dose-window” at 16O+-implantation into Si differs from Si(100) to Si(111). In SIMOX(100), an oxygen dose of 4 × 1017/cm2 into Si(100) is widely recognized as the dose-window when the acceleration energy is 180 keV. For the first time, our work shows that an oxygen dose of 5 × 1017/cm2 into Si(111) is the dose-window for the formation of SIMOX(111) substrates when the acceleration energy is 180 keV. The difference between dose-windows is caused by anisotropy of the crystal orientation during growth of the faceted buried SiO2. We also numerically analyzed the data at different oxidation velocities for each facet of the polyhedral SiO2 islands. Numerical analysis results show good agreement with the experimental data.

scholarly journals Performance of Turbulence Models and Near-Wall Treatments in Discrete Jet Film Cooling Simulations

1998 ◽  
Author(s):  
Jeffrey D. Ferguson ◽  
Dibbon K. Walters ◽  
James H. Leylek
Keyword(s):  
Experimental Data ◽  
Film Cooling ◽  
Turbulence Models ◽  
Viscous Sublayer ◽  
Reynolds Stress Model ◽  
Quality Data ◽  
Wall Functions ◽  
First Time ◽  
Near Wall ◽  
Non Equilibrium

For the first time in the open literature, code validation quality data and a well-tested, highly reliable computational methodology are employed to isolate the true performance of seven turbulence treatments in discrete jet film cooling. The present research examines both computational and high quality experimental data for two length-to-diameter ratios of a row of streamwise injected, cylindrical film holes. These two cases are used to document the performance of the following turbulence treatments: 1) standard k-ε model with generalized wall functions; 2) standard k-ε model with non-equilibrium wall functions: 3) Renormalization Group k-ε (RNG) model with generalized wall functions; 4) RNG model with non-equilibrium wall functions: 51 standard k-ε model with two-layer turbulence wall treatment; 6) Reynolds Stress Model (RSM) with generalized wall functions; and 7) RSM with non-equilibrium wall functions. Overall, the standard k-ε turbulence model with the two-layer near-wall treatment, which resolves the viscous sublayer, produces results that are more consistent with experimental data.

Strongly Superlinear Light Emission and Large Induced Absorption in Oxidized Porous Silicon Films

1998 ◽  
Vol 536 ◽  
Author(s):  
H. Koyama ◽  
P. M. Fauchet
Keyword(s):  
Porous Silicon ◽  
Thermal Effects ◽  
Light Emission ◽  
Laser Intensity ◽  
Excitation Intensity ◽  
Silicon Films ◽  
Free Standing ◽  
Induced Absorption ◽  
Cw Laser ◽  
Oxidized Porous Silicon

AbstractThe optical properties of oxidized free-standing porous silicon films excited by a cw laser have been investigated. It is found that samples oxidized at 800–950 °C show a strongly superlinear light emission at an excitation intensity of ∼10 W/cm2. This emission has a peak at 900–1100 nm and shows a blueshift as the oxidation temperature is increased. These samples also show a very large induced absorption, where the transmittance is found to decrease reversibly by ≤99.7 %.The induced absorption increases linearly with increasing pump laser intensity. Both the superlinear emission and the large induced absorption are quenched when the samples are attached to materials with a higher thermal conductivity, suggesting that laser-induced thermal effects are responsible for these phenomena.

Ultra-Low Power Light Emission via Avalanche and Sub-avalanche Breakdown in Suspended Carbon Nanotubes

ACS Photonics ◽  
2018 ◽  
Vol 5 (11) ◽  
pp. 4432-4436 ◽  
Author(s):  
Bo Wang ◽  
Sisi Yang ◽  
Lang Shen ◽  
Stephen B. Cronin
Keyword(s):  
Carbon Nanotubes ◽  
Low Power ◽  
Light Emission ◽  
Avalanche Breakdown ◽  
Ultra Low Power

scholarly journals Hysteresis in Muscle

2017 ◽  
Vol 27 (01) ◽  
pp. 1730003 ◽  
Author(s):  
Jorgelina Ramos ◽  
Stephen Lynch ◽  
David Jones ◽  
Hans Degens
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Hysteresis Loop ◽  
Mechanical Systems ◽  
Single Fibre ◽  
Scientific Disciplines ◽  
Main Components ◽  
First Time ◽  
Muscle Models ◽  
Clockwise Hysteresis

This paper presents examples of hysteresis from a broad range of scientific disciplines and demonstrates a variety of forms including clockwise, counterclockwise, butterfly, pinched and kiss-and-go, respectively. These examples include mechanical systems made up of springs and dampers which have been the main components of muscle models for nearly one hundred years. For the first time, as far as the authors are aware, hysteresis is demonstrated in single fibre muscle when subjected to both lengthening and shortening periodic contractions. The hysteresis observed in the experiments is of two forms. Without any relaxation at the end of lengthening or shortening, the hysteresis loop is a convex clockwise loop, whereas a concave clockwise hysteresis loop (labeled as kiss-and-go) is formed when the muscle is relaxed at the end of lengthening and shortening. This paper also presents a mathematical model which reproduces the hysteresis curves in the same form as the experimental data.

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