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Theoretical prediction of physical parameters of Ge x Sb20−x Te80 (x = 11, 13, 15, 17, 19) bulk glassy alloys

Sharma I, Maheshwari M

Materials Science Poland

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2014

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Vol. 32, No. 4

661--668

EN

Physical properties of GexSb20−xTe80 (x = 11, 13, 15, 17, 19) bulk glassy alloys are examined theoretically. Lone pair electrons are calculated using an average coordination number (hri) and the number of valence electrons, and are found to decrease with an addition of Ge. Mean bond energy (hEi) is proportional to glass transition temperature (Tg) and shows maxima near the chemical threshold. Cohesive energy of the system is calculated using chemical bond approach. A linear relation is found between cohesive energy, band gap (calculated theoretically and confirmed experimentally) and average heat of atomization. All these parameters are increasing with an increase in Ge content. A relation between average single bond energy and photon energy is discussed. Compactness of the structure is measured from the calculated density of the glass. An attempt is made to discuss the results in terms of structure of the glass or equivalently with average coordination number.

2

Recent advancement in metal containing multicomponent chalcogenide glasses

Singh A. K.

Opto-Electronics Review

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2012

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Vol. 20, No. 3

226-238

EN

Amorphous semiconductors or chalcogenide glasses are the key materials in modern optoelectronics to make comfortable life of our society. Understanding of physical properties (like microstructure, thermal, optical, electrical) of these materials is important for their different uses. Predominant study of physical properties of the metal containing multicomponent chalcogenide glasses have attracted much attention, due to their interesting variable features and wide range of structural network modifications. Structural modifications in these materials are usually described with respect to the values of structural units (or average coordination number). In significance to this, the present work demonstrates the chronological development in the field of chalcogenide glasses along with scanning electron microscopy (SEM) morphologies. Optical, electrical and thermal correlative properties of recent developed Se93-xZn2Te5Inx (0 ≤ x ≤ 10) metallic multicomponent chalcogenide glasses are discussed. Variation in SEM morphology, refractive index (n), extinction coefficient (K), optical energy band gap (Eg), electrical conductivity (δav), crystallization activation energy (Ec) and glass forming ability (GFA) with structural units of Se-Zn-Te-In glasses have been demonstrated in this study. Subjected materials thermal, optical and electrical parameters have been achieved higher and lower in a respective manner at the threshold structural unit value (r)

3

Distribution of electronic states in amorphous Zn-P thin films on the basis of optical measurements

Jarzabek B., Weszka J., Cisowski J.

Optica Applicata

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2008

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Vol. 38, nr 3

575-583

EN

Transmission and fundamental reflectivity studies, completed on amorphous Zn-P thin films, allowed us to obtain parameters describing the fundamental absorption edge, i.e., the optical pseudogap EG, Urbach energy EU and exponential edge parameter ET. All these data, together with the results of earlier transport measurements, have been utilized in developing simple models of electronic structure (distribution of electronic states) for amorphous Zn-P thin films of two compositions, i.e., Zn57P43 (near stoichiometry of Zn3P2) and Zn32P68 (near stoichiometry of ZnP2).

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On the microstructural origin of reversible photoinduced transformations in amorphus As₂Se₃

Shpotyuk O. I.

Opto-Electronics Review

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2003

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Vol. 11, No. 1

19-25

EN

A microstructural mechanism of photoinduced structural transformations in amorphous As₂Se₃ thin films was studied by IR Fourier-transform spectroscopy in the range of 300-100 cm⁻¹. It was shown that the stage of irreversible photostructural changes in the freshly-deposited films was connected with coordination of topological defects formation accompanied by homopolar chemical bonds switchings in heteropolar ones. By contrast, the reversible stage of photoinduced effects were caused by two different types of transformations-heteropolar bonds switching in homopolar ones, as well as heteropolar bridge bonds switching in short layer ones. Both processes were associated with the formation of anomalously coordinated topological defect pairs and atomic displacements at the medium-range ordering level.

5

Nonlinear dependence of optical gap of a-Si₁-xGex:H films on Ge content (x<0.4)

Dimova-Malinovska D.

Opto-Electronics Review

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2000

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Vol. 8, No. 4

382-384

EN

The dependence of optical band gap of a-Si₁-xGex:H films on Ge content is discussed. The films are deposited by magnetron co-sputtering of c-Si target with c-Ge chips on it in Ar + H₂ atmosphere. It has been observed that concentration of the bondeh hydrogen decreases with Ge content in the films. The results of study show that variation of the optical band gap of a-Si₁-xGex:H films on Ge concentration follows the nonlinear law. This is related to the nonlinear changes of H concentration in the films.