scholarly journals Резонансная микроволновая спектроскопия полупроводников с микронным разрешением

2022 ◽  
Vol 92 (3) ◽  
pp. 492
Author(s):  
А.Н. Резник ◽  
Н.В. Востоков
Keyword(s):  
Measurement Accuracy ◽  
Complex Impedance ◽  
Impedance Spectrum ◽  
Schottky Contacts ◽  
Local Method ◽  
Gaas Wafer ◽  
Charge Modulation ◽  
Spectrometer Calibration ◽  
Excess Resistance ◽  
Good Agreement

We have proposed and experimentally verified a local method of microwave resonant spectroscopy of semiconductors. The microwave circuit of the spectrometer based on the Cascade Microtech probe station is equipped with a coaxial resonator of special geometry. As result, the measurement accuracy of the previously developed volt-impedance spectroscopy method was greatly increased. A technique for spectrometer calibration and resonant measurements of the complex impedance of the probe-sample system has been developed. We have measured the impedance of test structures with Schottky contacts of 30 - 60 μm in diameter on a single-crystal GaAs wafer at several discrete frequencies in the range of 50 - 250 MHz. The nontrivial resistive properties of the structures are studied, which consist of the excess resistance that is 1–2 orders higher than the spreading resistance for the alternating current in the unperturbed region of the semiconductor. The discovered effect is presumably associated with the a.c. charge modulation on deep levels of the semiconductor. A model calculation of the impedance spectrum has been performed, which demonstrates a good agreement with the experimental spectra.

scholarly journals Микроволновая вольт-импедансная спектроскопия полупроводников

2020 ◽  
Vol 90 (11) ◽  
pp. 1944
Author(s):  
А.Н. Резник ◽  
Н.В. Востоков ◽  
Н.К. Вдовичева ◽  
В.И. Шашкин
Keyword(s):  
Electrical Potential ◽  
Complex Impedance ◽  
Impedance Spectrum ◽  
Antenna System ◽  
Electrical Potential Difference ◽  
Complex Impedance Spectrum ◽  
Homogeneous Sample ◽  
Semiconductor Interface ◽  
Constant Bias ◽  
Central Disk

We have tested experimentally the proposed method of microwave volt-impedance spectroscopy of semiconductors. The method allows to determine the local values of the semiconductor electrophysical parameters. The studies were performed on a homogeneous single-crystal GaAs wafer with a concentric antenna system formed on its surface. The resolution is determined by the diameter of the antenna central disk, which was amounted a = 12, 27, 57 μm. A constant bias voltage of 0 ≤ U ≤ 5 V was applied between the contact pads of the antennas. The complex impedance spectrum Z (f, U) of each antenna was measured using a Cascade Microtech probe station in the frequency range f = 0.1 - 10 GHz. The electrophysical characteristics of the semiconductor were determined from Z(f, U) spectra by the inverse problem solving. We have established the n-type for our semiconductor and determined the electrical potential difference on the metal-semiconductor interface. We have found as well the electron concentration, mobility and conductivity. Measurements of the same parameters by Hall four-probe method (giving the surface averaging) showed good mutual agreement of the results for the homogeneous sample under study.

scholarly journals An improved transmitter system to accurately measure wet-bulb temperature of air

2019 ◽  
Vol 52 (7-8) ◽  
pp. 1002-1007
Author(s):  
Liangwen Yan ◽  
Peng Yu ◽  
Sijung Hu ◽  
Qiu Gao ◽  
Wei Li ◽  
...  
Keyword(s):  
Real Time ◽  
Latent Heat ◽  
Measurement Accuracy ◽  
Cost Effective ◽  
Mean Value ◽  
Experimental Results ◽  
Iteration Algorithm ◽  
Good Consistency ◽  
The Mean ◽  
Good Agreement

A cost-effective measurement of wet-bulb temperature of air has great benefits to fulfill a growing demand of industry, cultivation agriculture, and medication. Applying an appropriate algorithm to wet-bulb temperature of air measurement can effectively improve the accuracy and speed of its measurement. The study aims to research how an improved transmitter system along with the latent heat–based iteration algorithm is used to precisely measure wet-bulb temperature of air. The work consists of (1) simulation of the iteration algorithm and (2) validation via experimental protocol. The simulation results through latent heat–based iteration algorithm were in good agreement ( R2≥ 0.99) with the reference. The performance of the improved wet-bulb temperature of air transmitter system was tested by a latent heat–based iteration algorithm experimental setup. The experimental results demonstrate that the improved wet-bulb temperature of air in a good consistency with commercial wet-bulb temperature of air in a range of temperature (15°C–34°C) and relative humidity (28.8%–76.2%). The Bland–Altman plot also shows that the mean value and the standard deviation of the differences between these two systems are 0.14°C and 0.29°C, respectively, which indicates that the improved wet-bulb temperature of air has a good agreement as well. Compared with the commercial wet-bulb temperature of air transmitter system, an advanced processor (STM32F103C8T6) and real-time operating system was applied in the improved wet-bulb temperature of air transmitter system. The experimental results show that its measurement accuracy is closer to the previous study. This study provides an alternative and cost-effective solution to accurately and real-time measure wet-bulb temperature of air.

Impedance loading servo pump system for excised canine ventricle

1982 ◽  
Vol 243 (2) ◽  
pp. H346-H350 ◽  
Author(s):  
K. Sunagawa ◽  
D. Burkhoff ◽  
K. O. Lim ◽  
K. Sagawa
Keyword(s):  
Digital Computer ◽  
Computer Control ◽  
Complex Impedance ◽  
Impedance Spectrum ◽  
Ventricular Volume ◽  
Analog Computer ◽  
Arterial System ◽  
Windkessel Model ◽  
Pump System ◽  
Hydraulic Impedance

To investigate ventricular-arterial system interaction, we have developed a hybrid-computer-controlled impedance loading servo pump system that enables us to impose a simulated arterial hydraulic impedance on an excised canine ventricle. An analog computer programmed to simulate a three-element Windkessel model of the arterial system computes instantaneous aortic flow from the instantaneous ventricular pressure. The time integral of this flow is used to command a volume servo pump system that controls the instantaneous ventricular volume. All parameter values in the loading system are controlled by a digital computer. The actual impedance spectrum generated by the system was reasonably close to that expected from the arterial model. The unique features of this system are the following. 1) The instantaneous volume of the ventricle, which is crucial information, can be measured. 2) If needed, the arterial impedance model can easily be reprogrammed to generate more complex impedance spectra. 3) The vascular parameters can be made nonlinear or time varying through the digital computer control.

scholarly journals The Performance of Commonly Used Surface-Based Instruments for Measuring Visibility, Cloud Ceiling, and Humidity at Cold Lake, Alberta

2021 ◽  
Vol 13 (24) ◽  
pp. 5058
Author(s):  
Faisal S. Boudala ◽  
Ismail Gultepe ◽  
Jason A. Milbrandt
Keyword(s):  
Measurement Accuracy ◽  
Microwave Radiometer ◽  
Temperature Sensors ◽  
Cloud Base ◽  
Significant Difference ◽  
Cold Lake ◽  
Cloud Base Height ◽  
Better Than ◽  
Good Agreement

Data from automated meteorological instruments are used for model validation and aviation applications, but their measurement accuracy has not being adequately tested. In this study, a number of ground-based in-situ, remote-sensing instruments that measure visibility (VIS), cloud base height (CBH), and relative humidity (RH) were tested against data obtained using standard reference instruments and human observations at Cold Lake Airport, Alberta, Canada. The instruments included the Vaisala FS11P and PWD22 (FSPW), a profiling microwave radiometer (MWR), the Jenoptik ceilometer, Rotronic, Vaisala WXT520, AES-Dewcell RH, and temperature sensors. The results showed that the VIS measured using the FSPWs were well correlated with a correlation coefficient (R) of 0.84 under precipitation conditions and 0.96 during non-precipitating conditions (NPC), indicating very good agreement. However, the FS11P on average measured higher VIS, particularly under NPC. When the FSPWs were compared against human observation, a significant quantization in the data was observed, but less was noted during daytime compared to nighttime. Both probes measured higher VIS compared to human observation, and the calculated R was close to 0.6 for both probes. When the FSPWs were compared against human observation for VIS < 4 km, the calculated mean difference (MD) for the PWD22 (MD ≈ 0.98 km) was better than the FS11P (MD ≈ 1.37 km); thus, the PWD22 was slightly closer to human observation than the FS11P. No significant difference was found between daytime and nighttime measured VIS as compared to human observation; the instruments measured slightly higher VIS. Two extinction parameterizations as functions of snowfall rate were developed based on the VFPs measurements, and the results were similar. The Jenoptik ceilometer generally measured lower CBH than human observation, but the MWR measured larger CBHs for values <2 km, while CBHs were underestimated for higher CBHs.

scholarly journals Electrical conductivity and dielectric behaviour of nanocrystalline La0.6Gd0.1Sr0.3Mn0.75Si0.25O3

RSC Advances ◽  
2018 ◽  
Vol 8 (17) ◽  
pp. 9103-9111 ◽  
Author(s):  
Ah Dhahri ◽  
E. Dhahri ◽  
E. K. Hlil
Keyword(s):  
Electrical Conductivity ◽  
Equivalent Circuit ◽  
Complex Impedance ◽  
Impedance Spectrum ◽  
Dielectric Behaviour ◽  
Complex Impedance Spectrum ◽  
Electrical Equivalent Circuit ◽  
Different Temperatures

A complex impedance spectrum for La0.6Gd0.1Sr0.3Mn0.75Si0.25O3 sample at different temperatures with electrical equivalent circuit.

ELECTRICAL AND DIELECTRIC PROPERTIES OF C7H12N2[H2PO4]2 ⋅ 1/2H2O

2012 ◽  
Vol 02 (04) ◽  
pp. 1230014 ◽  
Author(s):  
R. ELWEJ ◽  
A. OUESLATI ◽  
F. HLEL
Keyword(s):  
Dielectric Properties ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Complex Impedance ◽  
Impedance Spectrum ◽  
Electrical Equivalent Circuit ◽  
Compound C ◽  
Wide Range ◽  
Electrical And Dielectric Properties ◽  
Nyquist Plots

The electrical and dielectric properties of the compound C7H12N2[H2PO4]2 ⋅ 1/2H2O were investigated by the complex impedance spectroscopy, over a wide range of frequencies and temperatures, 600 Hz–5 MHz and 303–408 K, respectively. Besides, a detailed analysis of the impedance spectrum suggested that the electrical properties of the material at several temperatures and the electrical equivalent circuit have been proposed to explain the impedance results. Concerning the Nyquist plots, they clearly showed the presence of bulk and grain boundary. As for the imaginary part of modulus at several temperatures, it shows double relaxation peaks, thus suggesting the presence of grains and grain boundary conductions in the sample.

scholarly journals Comparison of Gait Analysis Between a Triaxial Accelerometer-Based Device and an Optical Motion Capture System

2020 ◽  
Author(s):  
Taisuke Ito ◽  
Yuichi Ota
Keyword(s):  
Gait Analysis ◽  
Motion Capture ◽  
Measurement Accuracy ◽  
Reaction Force ◽  
Correlation Coefficients ◽  
P Value ◽  
Motion Capture System ◽  
Optical Motion ◽  
Optical Motion Capture ◽  
Good Agreement

AYUMI EYE is an accelerometer-based gait analysis device that measures the 3D accelerations of the human trunk. This study investigated the measurement accuracy of the AYUMI EYE as hardware as well as the accuracy of the gait cycle extraction program via simultaneous measurements using AYUMI EYE, a ground reaction force (GRF), and an optical motion capture system called VICON. The study was conducted with four healthy individuals as participants. The gait data were obtained by simulating four different patterns for three trials each: normal walking, anterior-tilt walking, hemiplegic walking, and shuffling walking. The AYUMI EYE and VICON showed good agreement for both the acceleration and displacement data. The durations of subsequent stride cycles calculated using the AYUMI EYE and GRF were in good agreement based on the calculated cross-correlation coefficients (CCs) with an r value of 0.896 and p-value less than 0.05, and their accuracies for these results were sufficient.

Impedance Spectroscopy Applied to Metal Corrosion Study in Silicate Melts

2008 ◽  
Vol 595-598 ◽  
pp. 1119-1126 ◽  
Author(s):  
Christophe Rapin ◽  
Renaud Podor ◽  
J. Gassert ◽  
Michel Vilasi
Keyword(s):  
Impedance Spectroscopy ◽  
Electrochemical Techniques ◽  
Complex Impedance ◽  
Metal Corrosion ◽  
Complex Impedance Spectroscopy ◽  
Metallic Materials ◽  
Glass Melts ◽  
Glass Metal ◽  
Good Agreement

The determination of the corrosion processes of metallic materials in glass melts is of great interest for glass makers. Our attention has been specifically focussed on Cr-bearing alloys that form Cr2O3 layers when they are immersed in a silicate melt and offer a good resistance to melt corrosion. The comprehension of the corrosion processes has been extensively studied in the last 10 years using stationary electrochemical techniques. Results relative to the thermodynamic state were described. Complex impedance spectroscopy offers the possibility to determine the reaction kinetics in terms of limiting processes. Three chromium rods were directly immersed in molten glass at T=1050°C, maintained respectively in the active, passive and transpassive state and studied using electrochemical techniques. The results that are reported in this paper show a good agreement between complex impedance spectroscopy data, scanning electron microphotographies of the glass/metal interface and previous results obtained using stationary electrochemical techniques.

scholarly journals Frequency and temperature dependence behaviour of impedance, modulus and conductivity of BaBi4Ti4O15 aurivillius ceramic

2014 ◽  
Vol 8 (3) ◽  
pp. 145-153 ◽  
Author(s):  
Tanmaya Badapanda ◽  
Ranjan Harichandan ◽  
Sudhasu Nayak ◽  
Avinna Mishra ◽  
Sahid Anwar
Keyword(s):  
Relaxation Times ◽  
Complex Impedance ◽  
Negative Temperature ◽  
Impedance Spectrum ◽  
Nyquist Plot ◽  
Dielectric Study ◽  
Complex Impedance Spectrum ◽  
Debye Relaxation ◽  
Positive Side ◽  
Different Temperatures

In this work, we report the dielectric, impedance, modulus and conductivity study of BaBi4Ti4O15 ceramic synthesized by solid state reaction. X-ray diffraction (XRD) pattern showed orthorhombic structure with space group A21am confirming it to be an m=4 member of the Aurivillius oxide. The frequency dependence dielectric study shows that the value of dielectric constant is high at lower frequencies and decreases with increase in frequency. Impedance spectroscopy analyses reveal a non-Debye relaxation phenomenon since relaxation frequency moves towards the positive side with increase in temperature. The shift in impedance peaks towards higher frequency side indicates conduction in material and favouring of the long rangemotion of mobile charge carriers. The Nyquist plot from complex impedance spectrum shows only one semicircular arc representing the grain effect in the electrical conduction. The modulus mechanism indicates the non-Debye type of conductivity relaxation in the material, which is supported by impedance data. Relaxation times extracted using imaginary part of complex impedance (Z??) and modulus (M??) were also found to follow Arrhenius law. The frequency dependent AC conductivity at different temperatures indicates that the conduction process is thermally activated. The variation of DC conductivity exhibits a negative temperature coefficient of resistance behaviour.

Investigation of scattering from soundproof single sphere under external influence

2017 ◽  
Vol 12 (1) ◽  
pp. 73-82 ◽  
Author(s):  
E.Sh. Nasibullayeva
Keyword(s):  
Numerical Technique ◽  
Spherical Wave ◽  
Complex Impedance ◽  
Computer Time ◽  
Fast Method ◽  
External Influence ◽  
Scattering Field ◽  
Total Scattering Cross Section ◽  
Single Sphere ◽  
Good Agreement

The scattering from a single soundproof sphere is investigated during the passage of two types of waves: a spherical wave from a monopole radiation source and a plane wave. In solving the Helmholtz equation, a numerical technique based on the fast method of multipoles is used, which allows achieving high accuracy of the results obtained, and also minimizing computer time. The calculations are compared with known experimental data and a good agreement is obtained. Formulas are obtained for the main characteristic of the scattering field (the total scattering cross-section) for a sphere with an arbitrary acoustic impedance. Its dependence on the main parameters of the ”sphere – environment“ system for two kinds of the incident field is shown. A numerical parametric analysis of the value of the potential on the surface of a sphere for different values of its radius, complex impedance, the type of external influence, etc.

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