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Electrical and photoresponse characteristics of 8-(1H-indol-3-ylazo)-naphthalene-2-sulfonic acid/n-Si photodiode

Zedan Islam T., El-Menyawy E. M., Nawar H. H.

Opto-Electronics Review

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2019

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Vol. 27, No. 4

348--354

EN

In this paper, of primary interest is to synthesis 8-(1H-indol-3-ylazo)-naphthalene-2-sulfonic acid (INSA) and to evaluate the main parameters of Au/INSA/n-Si/Al diode in dark and under illumination. Different techniques are used for interpreting the proposed INSA chemical structure. The dark current-voltage measurements were achieved in the temperature range of 293−413K. It is noticed that INSA films modify the interfacial barrier height of classical Au/n-Si junction. At low applied voltages, the I–V relation shows exponential behavior. The values ideality factor, n, and the barrier height, φ, are improved by heating. The abnormal trend of n and φ is discussed, and a homogenous barrier height of 1.45 eV is evaluated. The series resistance is also calculated using Norde's function and it changes inversely with temperature. The space charge limited current ruled with exponential trap distribution dominates at relatively high potentials, trap concentration and carriers mobility are extracted. The reverse current of the diode has illumination intensity dependence with a good photosensitivity indicating that the device is promising for photodiode applications.

2

DC conductivity and Seebeck coefficient of nonstoichiometric MgCuZn ferrites

Madhuri W., Kiran S. R., Reddy M. P., Reddy N. R., Kumar K. V. S.

Materials Science Poland

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2017

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Vol. 35, No. 1

40--44

EN

Nonstoichiometric series of Mg0.5−xCuxZn0.5 Fe1.9 O4-δ where x = 0.0, 0.1, 0.15, 0.2 and 0.25 has been synthesized by conventional solid state reaction route. The single phase spinel structure of the double sintered ferrites was confirmed by X-ray diffraction patterns (XRD). The ferrite series was studied in terms of DC electrical conductivity and thermoelectric power in the temperature ranging from room temperature to 300 °C and 400 °C, respectively. It was observed that DC electrical conductivity and Seebeck coefficient α decreased with the increase in x. DC electrical conductivity was found to decrease by about 4 orders. All the compositions showed a negative Seebeck coefficient exhibiting n-type semiconducting nature. From the above experimental results, activation energy and mobility of all the samples were estimated. Small polaron hopping conduction mechanism was suggested for the series of ferrites. Owing to their low conductivity the nonstoichiometric MgCuZn ferrites are the best materials for transformer core and high definition television deflection yokes.

3

Niskotemperaturowe właściwości rezystorów RuO2-szkło

Mleczko K., Ptak P.

Zeszyty Naukowe Politechniki Rzeszowskiej. Elektrotechnika

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2015

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z. 34 [292], nr 2

275--294

PL

Przedmiotem badań były rezystory grubowarstwowe RuO2-szkło o znanym składzie, wykonane w warunkach laboratoryjnych. Przeprowadzono pomiary rezystancji i szumów nadmiarowych typu 1/f w funkcji temperatury, w zakresie 30 mK -300 K oraz w funkcji pola magnetycznego do 5 T. Rezystory RuO2-szkło dobrze nadają się do wykorzystania w roli kriogenicznych czujników temperatury ze względu na dużą czułość i małą magnetorezystancję. Porównanie tych parametrów z parametrami czujników komercyjnych pozwala stwierdzić, że są to przyrządu tej samej klasy. Badane rezystory charakteryzuje duży wzrost poziomu szumów nadmiarowych w zakresie temperatur kriogenicznych, przez co ograniczeniu ulega rozdzielczość pomiaru temperatury. Na podstawie pomiarów tych szumów określono rzeczywistą rozdzielczość pomiaru rezystancyjnych czujników temperatury. Dokonano także krytycznej analizy mechanizmów przewodnictwa najczęściej stosowanych do opisu rezystorów wykonanych na bazie RuO2. Pomiary temperaturowej zależności rezystancji pozwalają odrzucić model przewodnictwa skokowego zmiennozakresowego dla tego typu rezystorów. Z kolei pomiary szumów dają dobrą zgodność z jedną z teorii w ramach tego modelu przewodnictwa. Dla próbek badanych w pracy określono krytyczną koncentrację składnika metalicznego w warstwie rezystywnej, przy której następuje przejście metal-izolator.

EN

Thick film RuO2-glass resistors were studied. They were laboratory made, so their composition is well known. The measurements of resistance and 1/f excess noise as a function of temperature in the range of 30 mK - 300 K were performed. Also as a function of magnetic field in the range 0 – 5 T. The RuO2-glass resistors can be used as a cryogenic temperature sensors due to their high sensitivity and low magnetoresistance. A comparison of these parameters with the parameters of commercial sensors shows that they are the same class instruments. The resistors studied exhibit a large increase of excess noise level in the range of cryogenic temperatures, thus the temperature measurement resolution is limited. The noise measurements allowed to determine the actual measurement resolution of resistive temperature sensors. A critical analysis of conduction mechanisms frequently used to describe RuO2 resistors has also been performed. Measurements of temperature dependence of resistance allow to reject variable range hopping conductivity model for this type of resistors. On the other hand, the noise measurements give a good agreement with a theory within this model of conductivity. For the samples studied in the work a critical concentration of the metallic component in the resistive layer has been defined at which the metal-insulator transition occurs.

4

Electrical conduction in Ba(Bi0.5Nb0.5)O3 ceramics. Impedance spectroscopy analysis

Prasad K., Bhagat S., Amarnath K., Choudhary S. N., Yadav K. L.

Materials Science Poland

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2010

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Vol. 28, No. 1

317--325

EN

A new lead free perovskite ceramics Ba(Bi0.5Nb0.5)O3 was fabricated by a conventional ceramic technique at 1185 °C and subsequent sintering at 1200 °C in air atmosphere. The XRD analysis of Ba(Bi0.5Nb0.5)O3 powder indicated the formation of a single-phase monoclinic structure. The ac conductivity data were found to obey the power law and showed a negative temperature coefficient for the resistance behaviour. The ac conductivity values were used to evaluate the density of states at the Fermi level, minimum hopping length and activation energy of the compound. The correlated barrier hopping model was found to successfully explain the mechanism of charge transport in Ba(Bi0.5Nb0.5)O3.

5

Thick-film gas microsensors based on tin dioxide

Licznerski B.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2004

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Vol. 52, nr 1

37-42

EN

Semiconductive - resistive sensors of toxic and explosive gases were fabricated from nanograins of SnO2 using thick-film technology. Sensitivity, selectivity and stability of sensors working in different temperature depend on the way the tin dioxide and additives were prepared. A construction also plays an important role. The paper presents an attitude towards the evaluation of transport of electrical charges in semiconductive grain layer of SnO2, when dangerous gases appear in the surrounding atmosphere.