Document Details

Document Type : Thesis 
Document Title :
The growth and characteristic features of some compounds of the ternary thallium chalcogenide
الإنماء البلوري والملامح المميزة لبعض مركبات الثاليوم الثلاثية الشالكوجنيدية
 
Subject : Solid State Physics 
Document Language : Arabic 
Abstract : Narrow-gap semiconductors have attracted considerable interest due to their wide application in infrared optoelectronics. The ternary semiconducting challogeride with the formula ABX2 (X,B represent metal atoms, X represents Chalcogen atoms) have been studied intensively in recent years. Recently ternary thallium chalcogenides received a great deal of attention due to their optical and electrical properties ,in view of possible optoelectronic device application. These compounds recently held the attention of many physicists. TlBiTe2 and TlBiS2 is a narrow gap semiconductor belonging to the family of III-V-VI2 ternary compound of the general type TIBiX2 (X=Te, Se, S). The compounds TlBiTe2 and TlBiS2 have been the subjects of several studies because of this interesting features. In spite of their potential technological uses; in this work we choice TlBiTe2 and TlBiS2 as a subject of this investigation. Also nevertheless some physical properties of these two compounds have been scarcely reported, especially no detailed study of the Hall and switching effects have been performed. In view of the scarcity of the data on the properties of thallium Bismuth ditellurid , and thallium Bismuth disulphide, the present investigation gives the results of experimental studying of electrical conductivity, Hall effect and thermoelectric power as well as switching phenomenon, The aim of this project is to throw some light on the actual behavior of these compounds and reveal the contradiction of the previous results. The main characteristic parameters of the crystals can be evaluated from the experimental data. Special design for crystal growth from melt using a programmable muffle furnace, was used for growing single crystal of T1BiTe2 and T1BiS2. The product ingots were identified with X-ray analysis. The results of the present investigation can be summarized as follows: 1. Electrical conductivity and Hall effect was measured at the same time in the temperature range extends from 178 K to 568 K for T1BiTe2 and from 153 K to 573 K for TlBiS2. The energy gap has been found to be ∆Eg = 0.434 eV and ∆Eg = 0.441 eV for T1BiTe2 and T1BiS2 respectively. 2. The sample under test has p- type conductivity for TlBiTe2 while for TlBiS2 the conductivity of n-type. Also the present investigation involves thermoelectric power measurements of TlBiTe2 and TlBiS2 single crystals . These measurements enables us for the determination of many physical parameters such as carriers mobility's effective masses of free charge carriers diffusion coefficient and diffusion lengths , relaxation time of electrons and holes , as well as the figure of merit . The switching phenomena of our TlBiTe2 and TlBiS2 monocrystals was studied . Current – controlled negative resistance (CCNR) in both TlBiTe2 and TlBiS2 single crystals have been observed for the first time . It has been found that TlBiTe2 and TlBiS2 exhibits memory switching . The results strongly indicated that the phenomenon in our samples is very sensitive to temperature , light intensity and sample thickness . The current – voltage characteristics is symmetrical with respect to the reverse of the applied voltage and current for both compounds . The switching parameters of TlBiTe2 and TlBiS2 were checked under the influence of different factors of the ambient conditions . This mode of investigation (crystal growth and transport properties as well as switching phenomenon ) is the ideal way for finding out the possibility of making application for these compounds , especially in the field of energy conversion , devices and electronic engineering . 
Supervisor : Nagat Tawfeek Abbas 
Thesis Type : Doctorate Thesis 
Publishing Year : 1434 AH
2012 AD 
Number Of Pages : 305 
Added Date : Tuesday, December 2, 2014 

Researchers

Researcher Name (Arabic)Researcher Name (English)Researcher TypeDr GradeEmail
مريم حمد الحصينيAl-hossainy, Maryam hmaadInvestigatorDoctorate 

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