Dynamic Response of a Feedback Thermoresistive Electrical Substitution Pyranometer

1998 ◽  
Vol 120 (2) ◽  
pp. 126-130 ◽  
Author(s):  
R. C. S. Freire ◽  
G. S. Deep ◽  
P. C. Lobo ◽  
A. M. N. Lima ◽  
J. S. Rocha Neto ◽  
...  
Keyword(s):  
Thin Film ◽  
Response Time ◽  
Electrical Power ◽  
Wheatstone Bridge ◽  
Time Constants ◽  
Offset Voltage ◽  
True Value ◽  
Instrument Response ◽  
Order Of Magnitude ◽  
Electronic Amplifier

Calorimetric pyranometers use plane black thermal sensors which absorb solar radiation. If a thermoresistive transducer (sensor-detector combination) is used, the temperature measured is nearer the true value than for thermoelectric transducers. More importantly, the measurement of electrical power is much more accurate than the measurement of temperature. In commercial platinum (thermoresistive), thin film thermometers, the substrate produces transducer time constants an order of magnitude larger than for the best thermoelectric transducers. Use of an electronic amplifier with the thermoresistive sensor, forming one arm of a Wheatstone bridge and arranged in a negative feedback configuration, can reduce the overall response time considerably. Theoretical formulations of instrument response, taking into account the amplifier input offset voltage, are presented and the response time is estimated.

Hot-Wire Deposited Amorphous Silicon Thin-Film Transistors

1996 ◽  
Vol 424 ◽  
Author(s):  
R. E. I. Schropp ◽  
K. F. Feenstra ◽  
C. H. M. Van Der Werf ◽  
J. Holleman ◽  
H. Meiling
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
Gate Dielectric ◽  
Chemical Vapor ◽  
Current Crowding ◽  
Hot Wire ◽  
Saturation Regime ◽  
Silicon Thin Film ◽  
Order Of Magnitude

AbstractWe present the first thin film transistors (TFTs) incorporating a low hydrogen content (5 - 9 at.-%) amorphous silicon (a-Si:H) layer deposited by the Hot-Wire Chemical Vapor Deposition (HWCVD) technique. This demonstrates the possibility of utilizing this material in devices. The deposition rate by Hot-Wire CVD is an order of magnitude higher than by Plasma Enhanced CVD. The switching ratio for TFTs based on HWCVD a-Si:H is better than 5 orders of magnitude. The field-effect mobility as determined from the saturation regime of the transfer characteristics is still quite poor. The interface with the gate dielectric needs further optimization. Current crowding effects, however, could be completely eliminated by a H2 plasma treatment of the HW-deposited intrinsic layer. In contrast to the PECVD reference device, the HWCVD device appears to be almost unsensitive to bias voltage stressing. This shows that HW-deposited material might be an approach to much more stable devices.

Development of High-Efficiency Zn2SiO4:Mn Thin Films for Flat Panel Cathodoluminescent Displays

1997 ◽  
Vol 471 ◽  
Author(s):  
J. Liu ◽  
D. C. Morton ◽  
M. R. Miller ◽  
Y. Li ◽  
E. W. Forsythe ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electrical Conductivity ◽  
Response Time ◽  
Decay Time ◽  
High Efficiency ◽  
Fast Response ◽  
Flat Panel ◽  
Powder Phosphor ◽  
Fast Response Time

ABSTRACTZn2SiO4:Mn thin films were deposited and studied as thin film phosphors for flat panel cathodoluminescent displays. Crystallized films with improved electrical conductivity were obtained after conventional and rapid thermal annealings in a N2 environment at 850Xy11100 °C for 0.25 to 60 minutes. A maximum cathodoluminescent efficiency of 1.3 Lm/W was achieved under dc excitation at 1500 volts. The luminescent emission from these thin films was peaked around 525 nm. The decay time of these films was controlled in the range of 2 to 10 ms by varying the deposition and annealing parameters. The fast response time of these thin films overcomes the long decay limitation of the Zn2SiO4:Mn powder phosphor in practical display applications.

Low Frequency Measurements in Amorphous Wire for Studying GMI Effect

2011 ◽  
Vol 495 ◽  
pp. 201-204
Author(s):  
Polykseni Vourna
Keyword(s):  
Magnetic Field ◽  
Low Frequency ◽  
Major Change ◽  
Wheatstone Bridge ◽  
Amorphous Wire ◽  
Dc Voltage ◽  
Gmi Effect ◽  
Offset Voltage ◽  
Ac Current ◽  
The Magnetic Field

When a soft ferromagnetic material is flown by an ac current and a magnetic field is applied at the same time, a major change of its impedance is occurred. The aim of this paper is to investigate the influence of low frequency (1KHz-12KHz) ac current and the applied magnetic field on an amorphous magnetic wire (Co68Fe4.35Si12.5B15) without glass coating. For this purpose an experimental configuration has been setup, based on a Wheatstone bridge which receives an ac input signal from a frequency generator. The output is connected to the amorphous wire wrapped with a coil supplied by a dc voltage for the generation of the magnetic field. The output voltage pulse is measured for two cases a) The value of ac frequency is changing while the value of dc voltage applied to the coil remains constant (the magnetic field remains unchanged) and b) the magnetic field is changing while the ac frequency remains constant to a predefined value. Experimental results of the first scenario showed that when the frequency is altered a non-linear increase of the ac signal is observed at the output which shows an increase of the GMI effect and is related to the non-linearity of the wire’s permeability. For the second scenario the results showed an increase of the output signal offset (voltage) which also indicates an increase of the GMI effect.

scholarly journals Tripod-Loop Metasurfaces for Terahertz-Sensing Applications: A Comparison

2020 ◽  
Vol 10 (18) ◽  
pp. 6504
Author(s):  
Irati Jáuregui-López ◽  
Bakhtiyar Orazbayev ◽  
Victor Pacheco-Peña ◽  
Miguel Beruete
Keyword(s):  
Thin Film ◽  
Electric Field ◽  
Field Intensity ◽  
Electric Field Intensity ◽  
Ring Resonators ◽  
Film Sensor ◽  
Average Value ◽  
Sensing Applications ◽  
Order Of Magnitude ◽  
Hole Arrays

The high electric field intensity achieved on the surface of sensors based on metasurfaces (metasensors) makes them an excellent alternative for sensing applications where the volume of the sample to be identified is tiny (for instance, thin-film sensing devices). Various shapes and geometries have been proposed recently for the design of these metasensors unit-cells (meta-atoms) such as split ring resonators or hole arrays, among others. In this paper, we propose, design, and evaluate two types of tripod metasurfaces with different complexity in their geometry. An in-depth comparison of their performance is presented when using them as thin-film sensor devices. The meta-atoms of the proposed metasensors consist of a simple tripod and a hollow tripod structure. From numerical calculations, it is shown that the best geometry to perform thin-film sensing is the compact hollow tripod (due to the highest electric field on its surface) with a mean sensitivity of 3.72 × 10−5 nm−1. Different modifications are made to this structure to improve this value, such as introducing arms in the design and rotating the metallic pattern 30 degrees. The best sensitivity achieved for extremely thin film analytes (5–25 nm thick) has an average value of 1.42 × 10−4 nm, which translates into an extremely high improvement of 381% with respect to the initial hollow tripod structure. Finally, a comparison with other designs found in the literature shows that our design is at the top of the ranking, improving the overall performance by more than one order of magnitude. These results highlight the importance of using metastructures with more complex geometries so that a higher electric field intensity distribution and, therefore, designs with better performance can be obtained.

Response time constants of two commonly used dose-rate meters

1977 ◽  
Vol 50 (590) ◽  
pp. 149-150
Author(s):  
P. J. Gillespie ◽  
J. L. Alexander
Keyword(s):  
Response Time ◽  
Dose Rate ◽  
Time Constants

scholarly journals Dynamic characteristics of frequency-locked autodynes

2019 ◽  
Vol 30 ◽  
pp. 12009 ◽  
Author(s):  
Vladyslav Ya. Noskov ◽  
Kirill A. Ignatkov ◽  
Kirill D. Shaidurov
Keyword(s):  
Experimental Data ◽  
Numerical Modelling ◽  
Response Time ◽  
Dynamic Characteristics ◽  
Gunn Diode ◽  
Time Constants ◽  
Microwave Oscillators ◽  
Fast Movement ◽  
Signal Period

The results of research into the dynamic characteristics of microwave oscillators under the influence of both their own reflected radiation and external synchronising effect are presented. The basic relations for the analysis of signals during fast movement of the target are obtained, when the signal period is comparable to the autodyne response time constants. The results of numerical modelling of the characteristics are confirmed by the experimental data obtained on the example of an oscillator based on the Gunn diode of the 8-mm range.

scholarly journals Electrochromism in Electropolymerized Films of Pyrene-Triphenylamine Derivatives

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 73 ◽  
Author(s):  
Tian-Ge Sun ◽  
Zhi-Juan Li ◽  
Jiang-Yang Shao ◽  
Yu-Wu Zhong
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Response Time ◽  
Near Infrared ◽  
Contrast Ratio ◽  
Infrared Region ◽  
Cyclic Stability ◽  
Spectral Changes ◽  
Near Infrared Region ◽  
Ratio Response

Two star-shaped multi-triphenylamine derivatives 1 and 2 were prepared, where 2 has an additional phenyl unit between a pyrene core and surrounding triphenylamine units. The oxidative electropolymerization of 1 and 2 occurred smoothly to give thin films of polymers P1 and P2. The electrochemistry and spectroelectrochemistry of P1 and P2 were examined, showing two-step absorption spectral changes in the near-infrared region. The electrochromic properties, including contrast ratio, response time, and cyclic stability of P1 and P2 were investigated and compared. Thin film of P2 displays slightly better electrochromic performance than P1, with a contrast ratio of 45% at 1475 nm being achieved.

Hot-Wire Deposited Amorphous Silicon Thin-Film Transistors

1996 ◽  
Vol 420 ◽  
Author(s):  
R. E. I. Schropp ◽  
K. F. Feenstra ◽  
C. H. M. Van Der Werf ◽  
J. Holleman ◽  
H. Meiling
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
Gate Dielectric ◽  
Chemical Vapor ◽  
Current Crowding ◽  
Hot Wire ◽  
Saturation Regime ◽  
Silicon Thin Film ◽  
Order Of Magnitude

AbstractWe present the first thin film transistors (TFTs) incorporating a low hydrogen content (5 - 9 at.-%) amorphous silicon (a-Si:H) layer deposited by the Hot-Wire Chemical Vapor Deposition (HWCVD) technique. This demonstrates the possibility of utilizing this material in devices. The deposition rate by Hot-Wire CVD is an order of magnitude higher than by Plasma Enhanced CVD. The switching ratio for TFTs based on HWCVD a-Si:H is better than 5 orders of magnitude. The field-effect mobility as determined from the saturation regime of the transfer characteristics is still quite poor. The interface with the gate dielectric needs further optimization. Current crowding effects, however, could be completely eliminated by a H2 plasma treatment of the HW-deposited intrinsic layer. In contrast to the PECVD reference device, the HWCVD device appears to be almost unsensitive to bias voltage stressing. This shows that HW-deposited material might be an approach to much more stable devices.

Solar-Blind 4H-SiC Avalanche Photodiodes

2009 ◽  
Vol 615-617 ◽  
pp. 873-876 ◽  
Author(s):  
Stanislav I. Soloviev ◽  
Alexey V. Vert ◽  
Jody Fronheiser ◽  
Peter M. Sandvik
Keyword(s):  
Thin Film ◽  
Avalanche Photodiodes ◽  
Optical Filter ◽  
Leakage Currents ◽  
Avalanche Photodetectors ◽  
Rejection Ratio ◽  
Solar Blind ◽  
Order Of Magnitude

In this work, solar-blind UV 4H-SiC avalanche photodetectors were fabricated and tested in linear and Geiger modes. APDs with both PIN and separate absorption and multiplication (SAM) structures were investigated. PIN structures demonstrated higher quantum efficiencies while the SAM structure exhibit lower leakage currents. Deposition of a thin film optical filter on top of the devices was used to provide a high photon rejection ratio of (Stas add value here). However, an external filter showed a better photon rejection ratio compared to the deposited one by about one order of magnitude.

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