scholarly journals Influence of Surface and Bulk Defects on Contactless Resistivity Measurements of CdTe and Related Compounds

Sensors ◽  
2020 ◽  
Vol 20 (15) ◽  
pp. 4347
Author(s):  
Jan Franc ◽  
Roman Grill ◽  
Jakub Zázvorka
Keyword(s):  
Relaxation Time ◽  
Response Curve ◽  
Level Density ◽  
Radiation Detector ◽  
Deep Levels ◽  
Contactless Measurement ◽  
Contactless Method ◽  
Applied Bias ◽  
Single Exponential ◽  
Exponential Fit

We analyzed the influence of parameters of deep levels in the bulk and conditions on the surface on transient charge responses of semi-insulating samples (CdTe and GaAs). We studied the dependence on the applied bias step used for the experimental evaluation of resistivity in contactless measurement setups. We used simulations based on simultaneous solutions of 1D drift diffusion and Poisson’s equations as the main investigation tool. We found out that the resistivity can be reliably determined by the transient contactless method in materials with a large density of deep levels in the bulk (e.g., semi-insulating GaAs) when the response curve is described by a single exponential. In contrast, the materials with the low deep-level density, like semiconductor radiation detector materials (e.g., CdTe, CdZnTe, etc.), usually exhibit a complex response to applied bias, depending on the surface conditions. We show that a single exponential fit does not represent the true relaxation time and resistivity, in this case. A two-exponential fit can be used for a rough estimate of bulk material resistivity only in a limit of low-applied bias, when the response curve approaches a single-exponential shape. A decreasing of the bias leads to a substantially improved agreement between the evaluated and true relaxation time, which is also consistent with the approaching of the relaxation curve to the single-exponential shape.

23Na Spin-Lattice Relaxation Measurements in Dehydrated Na-X Zeolite

1996 ◽  
Vol 51 (5-6) ◽  
pp. 657-661 ◽  
Author(s):  
Mutsuo Igarashi ◽  
Noriaki Okubo ◽  
Shuichi Hashimoto ◽  
Deok Joon Cha ◽  
Ryozo Yoshizaki
Keyword(s):  
Relaxation Time ◽  
Room Temperature ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Raman Process ◽  
Relaxation Measurements ◽  
X Zeolite ◽  
Single Exponential

Abstract The spin-lattice relaxation time T1 of 23Na-NMR in a dehydrated Na-X zeolite has been measured from 20 to 300 K. The recovery curve is not single-exponential at all measured temperatures and T1-1 increases with the square of temperature around room temperature. The results are analyzed by assuming non-equivalent sites and by applying the theory of the Raman process based on covalency.

Kinetics of Shear Induced Micellar Association

1991 ◽  
Vol 248 ◽  
Author(s):  
L. E. Dewalt ◽  
H. D. Ou-Yang ◽  
M. W. Kim ◽  
S-N Liu ◽  
D. Pine ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Shear Rate ◽  
Sodium Salt ◽  
Dissociation Process ◽  
Shear Rates ◽  
Viscosity Measurements ◽  
Rheological Measurements ◽  
Large Fluctuations ◽  
Kinetics Of ◽  
Single Exponential

AbstractRheological measurements have been used to study the kinetics of shear induced association for rod-shape micelles formed by mixtures of ADHAB and salicylic-sodium salt. Pronounced hysteresis and large fluctuations were found in the stress-shear rate diagram. We investigate the association and dissociation mechanism through stress quench experiments where viscosity measurements study the system relaxation. The association process was found to be a single exponential with a relaxation time of about 1 minute, whereas the dissociation process was much slower and was non-exponential. In the semidilute regime, the critical shear rates increase with concentration, contradictory with existing theories.

Deep Levels in GaN Studied by Extrinsic Photoconductivity Measurement

1996 ◽  
Vol 449 ◽  
Author(s):  
Rong Zhang ◽  
Zhenchun Huang ◽  
Bo Guo ◽  
J. C. Chen ◽  
Li Yan ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Optical Absorption ◽  
Cross Section ◽  
High Resistance ◽  
Room Temperature ◽  
Deep Levels ◽  
Localized States ◽  
Absorption Cross ◽  
Gan Film ◽  
Photoconductivity Measurement

ABSTRACTModulation Extrinsic photoconductivity spectra between 1.44eV and 1.75eV of unintentionally n-doped high resistance GaN film grown by MOCVD are measured at room temperature by using wavelength adjustable Ti:Sapphire laser. We find that there are two major deep levels in the GaN material in the used photon energy range. The relaxation time of excess carriers controlled by those levels are in the order of 10−4sec. The concentration of localized states are determined as 1.8×108cm−3 and 2.5×109cm−3, respectively. A physical model is developed to explain the results and process the data. Using a new method we have determined the optical absorption cross section of deep levels are 1.5×10−17cm2 and 2.7×10−18cm2, respectively.

scholarly journals Picosecond pump-probe of carrier relaxation time in deep levels of HgCdTe

2012 ◽  
Vol 30 (6) ◽  
pp. 503-506
Author(s):  
Fa-Jun MA ◽  
Zhi-Feng LI ◽  
Lu CHEN ◽  
Wei LU
Keyword(s):  
Relaxation Time ◽  
Deep Levels ◽  
Carrier Relaxation ◽  
Pump Probe

scholarly journals Differential Inductive Sensing System for Truly Contactless Measuring of Liquids’ Electromagnetic Properties in Tubing

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5535
Author(s):  
Marc Berger ◽  
Anne Zygmanowski ◽  
Stefan Zimmermann
Keyword(s):  
Renal Replacement Therapy ◽  
Replacement Therapy ◽  
Flow Chamber ◽  
Electromagnetic Properties ◽  
Contactless Measurement ◽  
Contactless Method ◽  
Ferrite Core ◽  
Specific Flow ◽  
Sensing System ◽  
Chemical Process Control

Certain applications require a contactless measurement to eliminate the risk of sensor-induced sample contamination. Examples can be found in chemical process control, biotechnology or medical technology. For instance, in critically ill patients requiring renal replacement therapy, continuous in-line monitoring of blood conductivity as a measure for sodium should be considered. A differential inductive sensing system based on a differential transformer using a specific flow chamber has already proven suitable for this application. However, since the blood in renal replacement therapy is carried in plastic tubing, a direct measurement through the tubing offers a contactless method. Therefore, in this work we present a differential transformer for measuring directly through electrically non-conductive tubing by winding the tube around the ferrite core of the transformer. Here, the dependence of the winding type and the number of turns of the tubing on the sensitivity has been analyzed by using a mathematical model, simulations and experimental validation. A maximum sensitivity of 364.9 mV/mol/L is measured for radial winding around the core. A longitudinal winding turns out to be less effective with 92.8 mV/mol/L. However, the findings prove the ability to use the differential transformer as a truly contactless sensing system.

Deep Levels and Hydrogen Evolution in Hydrogenated Amorphous Silicon

1990 ◽  
Vol 192 ◽  
Author(s):  
Sufi Zafar ◽  
E. A. Schiff
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Temperature Dependence ◽  
Amorphous Silicon ◽  
Hydrogen Evolution ◽  
Deep Level ◽  
Level Density ◽  
Hydrogenated Amorphous Silicon ◽  
Deep Levels ◽  
Hydrogenated Amorphous

ABSTRACTTwo hydrogen-mediated models are applied to predicting the density of deep levels in hydrogenated amorphous silicon (a-Si:H) under variations in the material’s temperature and total hydrogen content. Both models depart from the assumption that hydrogen is bonded at two classes of sites, dangling bonds and weak bonds. The predictions of the two models for the temperature-dependence of the deep-level density are similar. The models differ in their treatment of the origins of the weak bonds; a model associating the weak bonds with the clustered phase of bonded hydrogen observed by nuclear magnetic resonance also appears to be in agreement with hydrogen evolution experiments.

scholarly journals 23Na Nuclear Spin-Lattice Relaxation in Dehydrated Zeolite NaY

1998 ◽  
Vol 53 (6-7) ◽  
pp. 442-446
Author(s):  
Mutsuo Igarashi ◽  
Noriaki Okubob ◽  
Ryozo Yoshizaki
Keyword(s):  
Relaxation Time ◽  
Nuclear Spin ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Zeolite Nay ◽  
Spin Lattice ◽  
Raman Process ◽  
Nuclear Spin Lattice Relaxation ◽  
Single Exponential

Abstract The spin-lattice relaxation time T1 of 23Na-NMR in dehydrated zeolite NaY has been measured from 26 to 300 K. The magnetization recovery curve is not single-exponential at all measured temperatures and T1-1 increases in proportion to the square of temperature above 200 K. The result is analyzed with a theory of the Raman process based on covalency. The value of T1 is compared with that of NaX in which the concentration of Na is about 2 times larger than in NaY.

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