Assunção, M. A. C. (1985) Effect of minor impurities on the electrical properties of Se and Se containing glasses. PhD thesis, University of Warwick.

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Abstract

A number of selenium glasses doped with halogens (Cl, Br, I), in the range of few p.p.m. up to U at %, were prepared in an oxygen-free atmosphere by melt quenching.

D.C. conductivity as a function of the temperature was measured and for the higher impurity concentration samples the measurement of the thermoelectric power, D.C. photoconductivity, electron spin resonance and optical absorption coefficient was also undertaken. Other supporting experiments included infrared spectrometry, differential scanning calorimetry, energy dispersive analysis of X-Rays and field effect.

X-Ray diffraction was used to check the lack of long-range order in each sample.

A general review of amorphous semiconductors is included with particular reference to their electronic and optical properties and the importance of defect states.

Results demonstrate the large effect of halogens on conductivity and that the conduction remains p-type with no observable E.S.R. signal. Data obtained are compared with those available in the literature and discussed within the framework of the CFQ-Mott theory. Tentative interpretation of the results is made via a "dangling bonds model" assuming a single particle acceptor level.

Additional complementary studies of a number of chalcogenide glasses doped with Br are also included. The effect of several other additives (Ag, Cu, Tl, Na, Sb, Al, Bi) on the D.C. conductivity and other properties of vitreous selenium is briefly investigated.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QC Physics
Library of Congress Subject Headings (LCSH):	Selenium -- Electric properties, Electric conductivity, Amorphous semiconductors -- Electric properties, Amorphous semiconductors -- Optical properties
Official Date:	December 1985
Dates:	Date Event December 1985 UNSPECIFIED
Institution:	University of Warwick
Theses Department:	Department of Physics
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	McMillan, P. W. (Peter Warwick)
Sponsors:	Universidade de Aveiro ; Instituto Nacional de Investigação Científica (Portugal) ; Invotan (Portugal)
Format of File:	pdf
Extent:	123 leaves : illustrations, photographs
Language:	eng

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