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Document Type |
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Thesis |
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Document Title |
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Preparation of some phases from the binary semiconductor systems Tl-Te and Tl-Se in crystalline form and measuring some of their physical properties تحضير بعض الأطوار من أشباه الموصلات الثنائية ذات النظام ثاليوم- تليريوم , ثاليوم- سيلينيوم في صورة بلورية وقياس بعض خواصها الفيزيائية . |
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Subject |
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Girls' College of Education in Jeddah |
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Document Language |
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Arabic |
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Abstract |
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Semiconductor compounds play an important role in technological development nowadays because of their attractive characteristics so they call the attention of many physicists to explore more and more of their hidden secrets. A2III B3VI semiconductor compounds find many application, and having promising properties.
Tl2Te3 and Tl2Se3 belong to a group of materials that have been and still are the subject of much intensive investigation because of their interesting characteristics.
High efficiency, low cost, local design constructed in our laboratory for crystal growth from melt based on Bridgman technique. This special design was used for grown Tl2Te3 and Tl2Se3 single crystal. The product ingots were identified with x-ray
analysis.
The obtained specimens were prepared with the required dimension for different measurements.
The results of the present investigations can be summarized as follow :-
1- Electrical conductivity and Hall coefficient.
An investigation has been carried out on the influence of temperature on the electrical conductivity and Hall phenomenon in a wild range of temperature under vacuum. The conductivity type throughout the entire temperature range was found to be P-type.
The energy gap, the depth of the impurity level was checked. The Hall mobility and the carrier concentration were determined. The scattering mechanism was also detected and discussed.
2- Thermoelectric power (TEP)
This phenomenon was investigated by employing the differential method in a wide range of temperature. Thermoelectric power was checked under vacuum. We notice that the crystals Tl2Te3 and Tl2Se3 were P-type.
Many physical parameters were estimated such as : effective masses diffusion coefficients. Relaxation times and diffusion length for both types of the carriers. Also the efficiency of the thermoelectric elements was evaluated.
3- Switching effect
The two specimens exhibit memory switching of the CCNR with s-shape .The phenomenon in our samples is very sensitive to the temperature intensity of light , and sample thickness. The switching parameters ( ith , vth , pth , Vh , Eth , Roff , Ron ) are checked under the influence of the different factors of the ambient conditions .
This mode of investigation (crystal growth and studying the transport properties in addition to switch phenomena) is the ideal way for finding out the possibility of making applications for these semiconductor compounds, especially in the field of energy conversion, devices, and electronic engineering. |
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Supervisor |
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Prof. Dr. Nagat Tawfeek Abbas |
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Thesis Type |
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Master Thesis |
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Publishing Year |
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1430 AH
2009 AD |
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Added Date |
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Sunday, January 3, 2010 |
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Researchers
| ليلى علي القحطاني | Alqahtani, Laila Ali | Researcher | Doctorate | |
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