GaAs Devices for Low Loss Power Rectification

1992 ◽  
Vol 281 ◽  
Author(s):  
L. V. Munukutla ◽  
S. H. Cheng ◽  
S. J. Anderson
Keyword(s):  
Barrier Height ◽  
Vapor Phase ◽  
High Voltage ◽  
Experimental Results ◽  
Low Loss ◽  
Barrier Heights ◽  
Schottky Rectifiers ◽  
Gaas Devices ◽  
Order Of Magnitude ◽  
Good Agreement

ABSTRACTHigh voltage GaAs Schottky rectifiers fabricated using vapor phase epitaxy have been observed to be an order of magnitude higher in switching speeds than silicon. Measured rectifier barrier heights deduced from the I-V and C-V plots were found to be in good agreement with previously reported values. Our experimental results show no correlation between the epilayer thickness and barrier height.

Reflexionserscheinungen bei Torsions-Alfvén-Wellen in inhomogenen Magnetfeldern/ Reflection Phenomena of Torsional Alfvén Waves in Inhomogeneous Magnetic Fields

1975 ◽  
Vol 30 (12) ◽  
pp. 1594-1599
Author(s):  
E. Räuchle ◽  
P. G. Schüller
Keyword(s):  
Magnetic Fields ◽  
Experimental Results ◽  
Numerical Calculations ◽  
Wave Frequency ◽  
Field Inhomogeneity ◽  
Cylindrical Plasma ◽  
Spatially Inhomogeneous ◽  
Strong Reflection ◽  
Order Of Magnitude ◽  
Good Agreement

Abstract The propagation of torsional Alfen waves in a cylindrical plasma is investigated. Superimposed on the plasma are various types of spatially inhomogeneous axisymmetric magnetic fields. Characteristic examples are: in the direction of propagation spatially decreasing, increasing and periodically modulated magnetic fields. The wave lengths are of the same order of magnitude as the characteristic lengths of the inhomogeneities. Strong reflection is observed which depends on wave frequency and strength of the field inhomogeneity. There exists good agreement between experimental results and numerical calculations.

Enhanced Thermionic Emission Cooling in High Barrier Superlattice Heterostructures

1998 ◽  
Vol 545 ◽  
Author(s):  
Ali Shakouri ◽  
Chris LaBounty ◽  
Patrick Abraham ◽  
Joachim Piprek ◽  
John E. Bowers
Keyword(s):  
Barrier Height ◽  
Thermoelectric Properties ◽  
Barrier Layer ◽  
Thermionic Emission ◽  
Experimental Results ◽  
Hot Electrons ◽  
Cooling Efficiency ◽  
Bulk Materials ◽  
Order Of Magnitude ◽  
Magnitude Improvement

AbstractThermionic emission current in heterostructures can be used to enhance thermoelectric properties beyond what can be achieved with conventional bulk materials. The Bandgap discontinuity at the junction between two materials is used to selectively emit hot electrons over a barrier layer from cathode to anode. This evaporative cooling can be optimized at various temperatures by adjusting the barrier height and thickness. Theoretical and experimental results for nonisothermal thermionic emission in heterostructures are presented. Single stage InGaAsP-based heterostructure integrated thermionic (HIT) coolers are fabricated and characterized. Cooling on the order of a degree over one micron thick barriers has been observed. Nonisothermal transport in highly doped tall barrier superlattices is also investigated. An order of magnitude improvement in cooling efficiency is predicted for InAlAs/InP superlattices.

Schottky barrier diode parameters of Ag/MgPc/p-Si structure

2012 ◽  
Vol 16 (07n08) ◽  
pp. 855-860 ◽  
Author(s):  
Mevlüde Canlıca ◽  
Mustafa Coşkun ◽  
Ahmet Altındal ◽  
Tebello Nyokong
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Forward Bias ◽  
Barrier Heights ◽  
Linear Behavior ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Frenkel Emission ◽  
Limited Conduction ◽  
Good Agreement

An Ag /Pc/p- Si Schottky barrier (SB) diode was fabricated. The current-voltage (I-V), capacitance-voltage (C-V) and conductance-voltage (G-V) measurements were carried out to determine the characteristic parameters such as barrier height, ideality factor and series resistance of the SB diode. The non-linear behavior of ln (I) vs. ln (V) and ln (I/V) vs. V1/2 plots indicated that the thermoionic emission theory can be applied to evaluate junction parameters for the investigated SB diode rather than space-charge limited conduction (SCLC) mechanism and bulk-limited Poole–Frenkel emission. The bulk doping concentration NB and fixed oxide charges Nf was determined from the measured high frequency C-V curve and was found to be 9.5 × 1014 cm-3 and 2.3 × 1013 cm-2, respectively. The values of barrier height obtained from Norde's function were compared with those from the forward bias current-voltage characteristic, and it was seen that there was a good agreement between barrier heights from both methods.

Inducing Frictional Force to Enhance the Transient Response in Beams

2019 ◽  
Vol 22 (2) ◽  
pp. 88-93
Author(s):  
Hamed Khanger Mina ◽  
Waleed K. Al-Ashtrai
Keyword(s):  
Numerical Analysis ◽  
Transient Response ◽  
Frictional Force ◽  
Damping Ratio ◽  
Experimental Results ◽  
Damping Capacity ◽  
Tightening Force ◽  
Contact Areas ◽  
Good Agreement ◽  
Ansys Workbench

This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.

PHOTOINDUCED NONLINEAR OCTUPOLAR POLARIZATION: TRANSIENT AND PERMANENT REGIMES

1996 ◽  
Vol 05 (04) ◽  
pp. 653-670 ◽  
Author(s):  
CÉLINE FIORINI ◽  
JEAN-MICHEL NUNZI ◽  
FABRICE CHARRA ◽  
IFOR D.W. SAMUEL ◽  
JOSEPH ZYSS
Keyword(s):  
Theoretical Analysis ◽  
Second Harmonic ◽  
Experimental Results ◽  
Polar Field ◽  
Rotational Spectrum ◽  
Dual Frequency ◽  
One Dimensional ◽  
Ethyl Violet ◽  
Disperse Red 1 ◽  
Good Agreement

An original poling method using purely optical means and based on a dual-frequency interference process is presented. We show that the coherent superposition of two beams at fundamental and second-harmonic frequencies results in a polar field with an irreducible rotational spectrum containing both a vector and an octupolar component. This enables the method to be applied even to molecules without a permanent dipole such as octupolar molecules. After a theoretical analysis of the process, we describe different experiments aiming at light-induced noncentrosymmetry performed respectively on one-dimensional Disperse Red 1 and octupolar Ethyl Violet molecules. Macroscopic octupolar patterning of the induced order is demonstrated in both transient and permanent regimes. Experimental results show good agreement with theory.

scholarly journals Comparison of Experimental and Numerical Transient Drop Deformation during Transition through Orifices in High-Pressure Homogenizers

2021 ◽  
Vol 5 (3) ◽  
pp. 32
Author(s):  
Benedikt Mutsch ◽  
Peter Walzel ◽  
Christian J. Kähler
Keyword(s):  
High Pressure ◽  
Visual Analysis ◽  
Imaging Technique ◽  
Extensional Flow ◽  
Droplet Breakup ◽  
Experimental Results ◽  
Drop Deformation ◽  
Droplet Deformation ◽  
Shadow Imaging ◽  
Good Agreement

The droplet deformation in dispersing units of high-pressure homogenizers (HPH) is examined experimentally and numerically. Due to the small size of common homogenizer nozzles, the visual analysis of the transient droplet generation is usually not possible. Therefore, a scaled setup was used. The droplet deformation was determined quantitatively by using a shadow imaging technique. It is shown that the influence of transient stresses on the droplets caused by laminar extensional flow upstream the orifice is highly relevant for the droplet breakup behind the nozzle. Classical approaches based on an equilibrium assumption on the other side are not adequate to explain the observed droplet distributions. Based on the experimental results, a relationship from the literature with numerical simulations adopting different models are used to determine the transient droplet deformation during transition through orifices. It is shown that numerical and experimental results are in fairly good agreement at limited settings. It can be concluded that a scaled apparatus is well suited to estimate the transient droplet formation up to the outlet of the orifice.

Quantum mechanical tunnelling: the missing term to achieve sub-kJ mol−1 barrier heights

2021 ◽  
Author(s):  
Sebastian Kozuch ◽  
Tim Schleif ◽  
Amir Karton
Keyword(s):  
Barrier Height ◽  
Quantum Mechanical ◽  
Effective Barrier Height ◽  
Quantum Tunnelling ◽  
Barrier Heights ◽  
Effective Barrier

Quantum tunnelling can lower the effective barrier height, creating a discrepancy between experiment and theory.

Opto-mechanical modeling and experimental implementation of an FBG-based piezoelectric bimorph actuator for high voltage sensing applications

2021 ◽  
pp. 1045389X2110282
Author(s):  
Raúl E Jiménez ◽  
José P Montoya ◽  
Rodrigo Acuna Herrera
Keyword(s):  
High Voltage ◽  
Good Accuracy ◽  
Correction Term ◽  
Experimental Results ◽  
Mechanical Modeling ◽  
Piezoelectric Bimorph ◽  
Linear Strain ◽  
Voltage Sensing ◽  
Sensing Applications ◽  
Experimental Implementation

This paper proposes a highly simplified optical voltage sensor by using a piezoelectric bimorph and a Fiber Bragg Grating (FBG) that can be used for high voltage applications with a relatively good accuracy and stability. In this work the theoretical framework for the whole opto-mechanical operation of the optical sensor is detailed and compared to experimental results. In the analysis, a correction term to the electric field is derived to account for the linear strain distribution across the piezoelectric layer improving the designing equations and giving more criteria for future developments. Finally, some experimental results from a laboratory scale optical-based high voltage sensing setup are discussed, and shown to be in excellent agreement with theoretical expected behavior for different voltage magnitudes.

scholarly journals 41Ca Concentrations in Modern Bone and Their Implications for Dating

Radiocarbon ◽  
1989 ◽  
Vol 31 (03) ◽  
pp. 305-310 ◽  
Author(s):  
Roy Middleton ◽  
David Fink ◽  
Jeffrey Klein ◽  
Pankaj Sharma
Keyword(s):  
Mass Spectrometry ◽  
Accelerator Mass Spectrometry ◽  
Isotope Enrichment ◽  
Terrestrial Rock ◽  
Order Of Magnitude ◽  
Cow Bone ◽  
Good Agreement

We have made the first measurements without pre-enrichment of 41Ca in terrestrial rock and bone samples using accelerator mass spectrometry. Although the results in tufa deposits from Egypt are in good agreement with the saturation value of 8×10-15 predicted by Raisbeck and Yiou (1979), the average 41Ca:40Ca ratio of 2×10-15 (range: 0.6 to 4.2×10-15) that we measure in modern bone is an order of magnitude lower than that obtained previously by Henning, et al (1987) on a cow bone that was measured using AMS following isotope enrichment. The low value and the variability (more than a factor of seven) of the 41Ca:40Ca ratio in modern bone make the possibility of dating bones using 41Ca unlikely.

Simulation of Sphere’s Motion Induced by Shock Waves

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Dan Igra ◽  
Ozer Igra ◽  
Lazhar Houas ◽  
Georges Jourdan
Keyword(s):  
Shock Waves ◽  
Drag Coefficient ◽  
Drag Force ◽  
Stationary Flow ◽  
Experimental Results ◽  
Experimental Findings ◽  
Sphere Drag ◽  
Simulation Scheme ◽  
Good Agreement

Simulations of experimental results appearing in Jourdan et al. (2007, “Drag Coefficient of a Sphere in a Non-Stationary Flow: New Results,”Proc. R. Soc. London, Ser. A, 463, pp. 3323–3345) regarding acceleration of a sphere by the postshock flow were conducted in order to find the contribution of the various parameters affecting the sphere drag force. Based on the good agreement found between present simulations and experimental findings, it is concluded that the proposed simulation scheme could safely be used for evaluating the sphere’s motion in the postshock flow.

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