Synthesis and thermoelectric power measurements of TlGaSe 2 single crystals
TlGaSe2single crystals were grown by modified Bridgman method. Thermoelectric power measurement were carried out in a brass working chamber designed for this purpose, allow measurements in a wide range of temperature under vacuum. The experimental results indicates that TlGaSe2 is of p-type conductivity. Throughout these measurements, various parameters such as effective mass of charge carriers, carrier mobility, diffusion coefficient, relaxation time and diffusion length for both majority and minority carriers were found. In addition to these pronounced parameters, the efficiency of the thermoelectric element (figure of merit) was evaluated, which leads to better application in many fields. [A. T. Nagat, S. A. Hussein, S. E. Al Garni. Synthesis and thermoelectric power measurements of TlGaSe2 single crystals. Life Sci J 2014;11(8):418-422]. (ISSN:1097-8135). http://www.lifesciencesite.com. 54
The Growth of p-Type A^{III} B^{III} C_2^{V I} Single Crystals
ABC I 2 single crystals were grown by the modified Bridgman-Stockbarger method, a procedure similar to direct freezing in our crystal growth laboratory. ABC I 2 compounds are collected into two groups (III. group: TI, Ga, In and VI. group: Se, S, Te): 1. TlGaSe2, TlGaS2 and TlInS2 have layer structure. 2. TlInSe2, TlInTe2 and TlGaTe2 have chained structure. The main reasons such crystals grown with this method is similar to the direct freezing method because 1) quality of crystals is the same as crystals grown by other methods, and 2) growth time of crystals is shorter by about 5-10 days. None of the grown crystals had cracks and voids on the surface. Freshly cleaved crystals had a mirror-like surface and there was no need for mechanical or chemical polishing. The X-ray Laue back reflection method was used to test the crystallinity of the prepared samples. It was found that the crystals was p-type by hot probe technique. The ingots produced were single crystals and the useful region of single crystal was approximately 90% of the bulk.
Growth and optical properties of TlGaSe2 and β-TlInS2
Abstract TlGaSe2 and β-TlInS2 were studied for crystal growth and optical properties. Both materials have wide transparency regions, from 0.61 to 20 μm for the former and 0.5 to 12.5 μm for the latter. X-ray studies of single crystals show that these compounds are monoclinic, space group P2 1 m . Raman spectra are presented.