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Spectroscopic investigations of polycrystalline InxSb20−xAg10Se70 (0 6 x 6 15) multicomponent chalcogenides

Sharma R., Sharma S., Kumar P., Chander R., Thangaraj R., Mian M.

Materials Science Poland

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2016

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Vol. 34, No. 4

794--799

EN

The composition dependence of physical properties of chalcogenides has recently been studied for their phase change properties and energy conversion. In the present work, we report the structure, composition, optical and Raman spectroscopy results for bulk polycrystalline InxSb20-xAg10Se70 (0 ≤ × ≤ 15) samples. The phase quantification and composition have been studied by using XRD and EDX techniques. The alloy composition up to 5 at.% of indium resulted in crystallization of AgSbSe2, while further increase in In content favored the formation of another chalcopyrite AgInSe2 phase yielding the solid solutions for this alloy system. A decrease in band gap up to x = 5 followed by its increase with an increase in indium concentration has been observed. The variations in shape and position of characteristic Raman bands has been used for understanding the structural modifications of the network with the variation in indium content.

2

Optical and electrical characterization of BixSe1−x thin films

Ibrahim M. M., Fayek S. A., Amin G. A. M., Elnagar D. M.

Materials Science Poland

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2016

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Vol. 34, No. 2

460--469

EN

Bulk samples of the BixSe1-x system with (x = 0, 5, and 10) were prepared using conventional melt quenching technique. Thin films were then deposited by thermal evaporation technique under high vacuum conditions from the prepared bulk samples. Effect of Bi substitution on surface morphology, electrical and optical properties of BixSe1-x thin films was studied. X-ray diffraction studies showed the formation of nanocrystalline clusters at Bi concentration x = 10. Formation of these clusters resulted in a rough surface which was confirmed by AFM measurements. The film surface was smooth, with RMS roughness of 0.0124 nm for Bi5Se95. For Bi10Se90, the RMS roughness increased to 3.93 nm indicating the formation of Bi2Se3 clusters. A simple hot probe technique showed a transition from p-type to n-type due to Bi incorporation. Charge transport mechanisms were investigated by temperature dependent DC electrical conductivity measurements in the temperature range of 209 K to 313 K. Electrical activation energy (ΔE) of the films with different Bi concentrations was found to exhibit a notable change at the p to n transition. At low temperature, the conduction was in reasonable agreement with Mott’s condition of variable range hopping. Mott parameters and the density of localized states near Fermi level were evaluated and correlated with the structural changes resulting from Bi addition. In addition, a red shift of the optical absorption edge of the films under study caused by Bi-Se substitution was observed. Slight changes in the optical parameters were observed with the γ-irradiation. Addition of Bi atoms could be used to tailor the structural, electrical and optical properties of chalcogenide materials such as junctionless photovoltaic devices.

3

Studies on Inx(As2Se3)1-x thin films using variable angle spectroscopic ellipsometry (VASE)

Amin G. A. M.

Materials Science Poland

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2015

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Vol. 33, No. 3

501--507

EN

The results of multi-angle ellipsometrical measurements of thermally evaporated In_x(AsSe₃)_1-x (x = 0, 0.01, 0.05) films are presented. Optical parameters n and Eg of thin In_x(AsSe₃)_1-x films show that indium atoms were incorporated into the host matrix of AsSe₃ forming distinct features depending on the indium concentration. Refractive index, n, was found to decrease with the addition of In to the binaryAsSe₃. The real and imaginary parts of the dielectric function, ε' and ε" were also calculated from the obtained data and correlated with In concentration. It was found that ε' decreases with the increaseof In content while ε" increases with the increase of In content. Absorption edge is shifted towards lower photon energy with the increase of In content. As a result, the optical energy gap decreases with increasing In content. This has been correlated with the chemical character of the additive as well as with the structural and bonding aspects of the amorphous composition. Nonlinear optical constants (Χ⁽³⁾ and n₂) were determined from linear optical parameters using semi-empirical relations in the long wavelength limit.

4

Photo-induced changes in arsenic selenide films

Moharram A. H., Mansour S. A., Al-Marzouki F., Hendi A. A., Rashad M.

Materials Science Poland

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2013

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Vol. 31, No. 1

139-145

EN

The spectral dependence of the transmittance and reflectance of thermally-evaporated amorphous AsxSe100x (where x = 20 and 40 at.%) films was measured in the wavelength range of 190 - 900 nm. A procedure was given for accurate determination of the film thickness using a standard method of numerical differences from the experimental data. The process of indirect electronic transitions was found to be responsible for the photon absorption. The variation of the energy band gap with the exposure time was investigated. Amorphous-crystalline transformations occurring as a result of photoexposure have been confirmed by the structural studies of the As20Se80 specimens using the scanning electron microscope and transmission electron microscope. Photodarkening relaxation under light exposure of the well annealed films was studied and the relaxation process has been described by the stretched exponential function (SEF).

5

Photoinduced degradation in the electrical properties of normally and obliquely deposited As2Se3 thin films

Bhardwaj P., Shishodia P. K., Mehra R. M.

Materials Science Poland

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2007

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Vol. 25, No. 1

69--77

EN

Dark conductivity in As2Se3 films was measured in the temperature range 300-400 K. It was found to be of the doubly activated type in high- and low-temperature ranges. The experimental results were analysed using the Meyer-Neldel rule. The effect of light soaking on the electrical transport properties of normally and obliquely deposited As2Se3 thin films were examined. It has been observed that light soaking results in the degradation of photocurrent, which nearly saturates in an hour. Dark conductivity is fqund to be smaller after light soaking than without it.

6

Porównanie stałych sieciowych czteroskładnikowych chalkogenidków molibdenu

Niewiarowska D., Cybulski Z. A., Ziółkowska D.

Chemik

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2005

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Vol. 58, nr 9

468-470

PL

Potrójne chalkogenidki o wspólnej postaci ABX4 (A=Ti, B=Mo, X=S, Se, Te) interkalowano litem oraz miedzią. Ustalono, że związki miedzi są bardziej odporne na wpływ czynników powietrza atmosferycznego, niż interkalaty zawierające lit. Dla wszystkich rozważanych związków komórki elementarne wywskaźnikowano w układzie jednoskośnym, uzyskując bardzo dobrą zgodność pomiędzy danymi doświadczalnymi i teoretycznymi. Wyliczone wartości stałych sieciowych dobrze ze sobą korespondują z wyjątkiem stałej "a" dla LiTiMoSe4. W przypadku tellurków tytanowo-molibdenowych interkalowanych miedzią stwierdzono także, że większa średnica atomu "gościa" powoduje wzrost stałej sieciowej "c".

EN

Ternary chalcogenides with common formula ABX4 (A=Ti, B=Mo, X=S, Se, Te) were intercalated with lithium and copper. It was stated that the copper compounds were more resistant to influences of atmospheric air components then the intercalates containing lithium. Very good agreement between the experimental and theoretical data confirms that for all the compounds under discussion the elementary cells can be described in the monoclinic system. The calculated values of the lattice constants are well corresponding wite each other with the exception of the constant a for LiTiMoSe4. Moreover, in the case of titanium-molybdenum tellurides intercalated with copper it was ascertained that greater ion diameter of the "quest" atom increases the lattice constant c.

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Photoluminescence and structural properties of selected wide-gap II-VI solid solutions.

Firszt F., Łęgowski S., Męczyńska H., Sekulska B., Szatkowski J., Paszkowicz W., Marczak M.

Opto-Electronics Review

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1999

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Vol. 7, No. 2

87-92

EN

This work presents results of investigations of photoluminescence and structural properties of ternary Zn₁-xBexSe, Cd₁-xMgxSe, Zn₁-xMgxSe and quaternary Cd₁-x-yMgxZnySe, Zn₁-x-yBexMgySe, Zn₁-xMgxSe₁-ySy mixed crystals. These crystals were grown from the melt by the high-pressure Bridgman method. Zn₁-xMgxSe and Zn₁-xSrxSe were also obtained by annealing of ZnSe crystals in evacuated quartz ampoules containing Mg or Sr metal. It has been found that admixing of Mg into ZnSe favours the formation of wurtzite Zn₁-xMgxSe while Besphalerite Zn₁-xBexSe structures. Low temperature (40 K) photoluminescence spectra consist of exciton, edge and deep levels emission bands. For most of investigated crystals the emission corresponding to the highest photon energy line in luminescence spectrum is observed up to room temperature.