Wyniki wyszukiwania - Biblioteka Nauki

1

Wpływ kształtu modulowanego promieniowania optycznego na czułość napięciową detektora piroelektrycznego

100%

Odon A.

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tom R. 58, nr 11

997-999

PL

Badania zależności czułości detektora piroelektrycznego od częstotliwości powinny być przeprowadzane przy zastosowaniu sinusoidalnie modulowanego promieniowania pobudzającego detektor. W praktyce eksperymentalnej często stosowane są elektromechaniczne modulatory, które zapewniają wytworzenie quasi-prostokątnego lub quasi-trapezowego kształtu przebiegu mocy promieniowania. Wyznaczona w ten sposób wartość czułości napięciowej detektora może być obarczona dużym błędem. W artykule przedstawiono rezultaty badań symulacyjnych, których celem jest wyznaczenie zależności czułości napięciowej od częstotliwości dla modelu detektora piroelektrycznego zaimplementowanego w programie MATLAB-Simulink i dokonanie oceny błędu pomiaru czułości spowodowanego zastosowaniem niesinusoidalnych przebiegów mocy promieniowania pobudzających detektor piroelektryczny.

EN

The voltage responsivity of a pyroelectric detector is one of the most important parameters characterizing its measuring properties. Sinusoidally modulated optical radiation should be used for experimental measuring of the pyroelectric detector responsivity. In practice rotating disk choppers are commonly used as a source of modulated optical signals in experimental setups. A disadvantage of using optical choppers is that the produced radiation may have a square or trapezoidal waveform. In the paper the results of simulation studies of the pyroelectric detector frequency response for sinusoidal, square and trapezoidal shape of the modulated radiation are presented. The simulation studies were carried out for the pyroelectric detektor model with use of program MATLAB-Simulink. Values of the main parameters of this detector were precisely specified. The frequency dependence of the pyroelectric detector voltage responsivity for different shapes of the absorbed radiation waveform is shown in Fig. 2. The simulation results show that the responsivity of the detector excited by a square wave of radiation has a much higher value (up to several hundred percent) in comparison to that obtained with sinusoidal modulation of radiation, especially at low frequencies. Trapezoidal modulation produces a much smaller error than the square wave modulation.

2

Influence of doping on the performance of GaAs/AlGaAs QWIP for long wavelength applications

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Billaha A. , Das M. K.

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2016

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tom Vol. 24, No. 1

25--33

EN

Effect of doping and other device parameters on inter sub−band transition in the well, responsivity and dark current of GaAs/AlxGa1-xAs quantum well infrared photodetector (QWIP) is investigated using theoretical model. 2X2 Hamiltonian method is used to calculate Eigen energy states in this modelling. Results show that peak absorption, responsivity and spectral broadening width increase nonlinearly with increasing doping concentration in the well. Peak absorption coefficient increases with increase in well width also. Moreover, with increase in mole fraction of Al in AlxGa1-xAs barrier, the inter sub-band absorption is enhanced but, peak wavelength of absorption shifts towards shorter wavelengths. Dark current density depends on both, the doping concentration and applied bias.

3

Fabrication and photoelectrical properties of a novel violet and blue enhanced SINP silicon photovoltaic device

100%

Bo H. , Ma Z. Q. , Jing X. , Lei Z. , Sheng Z. N. , Feng L. , Feng L. , Cheng S. , Ling S. , Jie M. X. , Jie M. X. , Yue Z. C. , Shan Y. Z. , Ting Y. Y.

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2009

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tom Vol. 39, nr 3

547-560

EN

A novel ITO/SiO2/np-silicon violet and blue enhanced photovoltaic device with SINP structure has been fabricated by thermal diffusion of phosphorus. The shallow junction was formed to enhance the spectral responsivity within the wavelength range of 400-600 nm. An ultrathin silicon dioxide was thermally grown at low temperature and RF sputtering of ITO antireflection coating to reduce the reflected light and enhance the sensitivity. The crystalline structure, optical and electric properties of ITO film were determined by an XRD, UV-VIS spectrophotometer, a four point probe and the Hall effect measurement, respectively. The results show that ITO film has high quality. The current-voltage (I-V) characteristics, spectral response and responsivity of the photovoltaic device with high quantum efficiency of violet SINP and deep junction SINP structure were calculated and analyzed in detail.

4

Numerical analysis of SiGeSn/GeSn interband quantum well infrared photodetector

86%

Pareek P. , Das M. K. , Kumar S.

Opto-Electronics Review

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2018

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tom Vol. 26, No. 2

149--157

EN

In this paper, detailed theoretical investigation on the frequency response and responsivity of a strain bal-anced SiGeSn/GeSn quantum well infrared photodetector (QWIP) is made. Rate equation and continuity equation in the well are solved simultaneously to obtain photo generated current. Quantum mechanical carrier transport like carrier capture in QW, escape of carrier from the well due to thermionic emission and tunneling are considered in this calculation. Impact of Sn composition in the GeSn well on the frequency response, bandwidth and responsivity are studied. Results show that Sn concentration in the GeSn active layer and applied bias have important role on the performance of the device. Significant bandwidth is obtained at low reverse bias voltage, e.g., 200 GHz is obtained at 0.28 V bias for a single Ge0.83 Sn0.17 layer. Whereas, the maximum responsivity is of 8.6 mA/W at 0.5 V bias for the same structure. However, this can be enhanced by using MQW structure.

5

Quantum dot infrared photodetector

86%

Liu H. C.

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2003

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tom Vol. 11, No. 1

1-5

EN

This paper discusses key issues related to the quantum dot infrared photodetector (QDIP). These are the normal incidence response, the dark current, and the responsivity and detectivity. We attempt to address the following questions of what is QDIP' s potential, what is lacking, and what is needed to make the device interesing for practical applications. It is argued that so for the present QDIP devices have not fully demonstrated the potential advantages. Representative experimental results are compared with characteristics of quantum well infrared photodetectors. Areas that need improvements are pointed out.

6

Altering identities. Possibilities of understanding identity in phenomenological pedagogy

71%

Breil P.

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nr 2

225-235

EN

In one way or another, the other plays an important role in educational settings. Over the last few decades, the recourse to philosophical phenomenology has proved to be helpful for the discussion of this topic. Coming from this thematic direction, this article focuses on the other in its constitutive function for the construction of identity. Both within the phenomenologist Bernhard Waldenfels’ theory of responsivity as well as in the pedagogue Wilfried Lippitz’ theory of alterity, the other is a structural part of the self. It will be shown that within these theories the possible dangers of an encounter with the other cannot be addressed in an adequate way. However, this is especially important in educational contexts. Therefore, with regard to the philosophies of Jean‐Paul Sartre and Simone de Beauvoir, I would like to present two additional phenomenological approaches from which the pedagogical discussion can benefit. Both Sartre and Beauvoir put great focus on possible obstacles regarding the en‐ counter with the other. Whereas Sartre identifies negativity as an essential part of human existence, Beauvoir enriches these thoughts with an ethical component. Against the background of these philosophies, the other comes into view as a possible source of both objectification and empowerment. Lastly, the article shows that an implementation of these considerations in teacher training can lead to a deeper understanding of the constitution of identity and the inherent possibilities of any interaction with the other.