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Substrate temperature effect on the nanoscale multilayer ZnS/Ag/ZnS for heat mirror application

Kavei G., Nikbin S.

Materials Science Poland

2015

Vol. 33, No. 4

760--766

Nanoscale multilayers of ZnS/Ag/ZnS were deposited on Corning glass substrates at different substrate temperatures. The depositions were carried out in high vacuum using electron beam deposition technique at 20, 60, 100 and 150 degrees C, respectively. The optical and electrical performance of each single layer and the accomplished ZnS/Ag/ZnS multilayer system were characterized using spectroscopic ellipsometry analysis, XRD and finally AFM. Based on these analyses and associated theories, such as the characteristic matrix theory, the optimized multilayer system was speculated and tested. Crystallographic structures of the films were studied by X-ray diffraction. In addition to X-ray diffraction, morphological characterizations were carried out by AFM in order to observe the deposited particle size, packing and roughness of the films. The optimum performance was achieved at the substrate temperature of 60 degrees C.

(Bi2Te3)0:25(Sb2Te3)0:75 crystal structure improvements with excess Te as studied by AFM, SEM, EBSD and XRD

Kavei G., Ahmadi K., Shadmehr A. K., Kavei A.

Materials Science Poland

2011

Vol. 29, No. 2

144--151

(Bi2Te3)x(Sb2Te3)1-x solid solutions with x = 0:2, 0.25 and 0.3 - p type thermoelectric compounds with an excess of Tellurium dopant up to 4 wt% were crystallized. By increasing the Bi2Te3 content in the Bi-Sb-Te system, the hole concentration decreased and in consequence caused an optimum Seebeck coefficient and a decrease in electrical conductivity and thermal conductivity, thus resulting in an increase in the figure of merit at x = 0:25. The results showed that optimum thermoelectric properties can be achieved for a mixture of x = 0:25 with 3 wt% Te added. Structural characterizations of this compound in the absence and presence of the dopant were carried out by means of X-Ray diffraction measurement, scanning electron microscopy, electron backscattering diffraction and atomic force microscopy. Detailed analyses confirm that the improvements in thermoelectric parameters due to the intrinsic structure and minimum defects during crystallization of the compounds result from the excess of Te.