Microstructure Control and Crystallization Kinetics in Amorphous Cadmium-Germanium - Arsenide (Devitrification, Differential Scanning, Calorimetry)
Speyer, Robert Fredrick
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https://hdl.handle.net/2142/71707
Description
Title
Microstructure Control and Crystallization Kinetics in Amorphous Cadmium-Germanium - Arsenide (Devitrification, Differential Scanning, Calorimetry)
Author(s)
Speyer, Robert Fredrick
Issue Date
1986
Department of Study
Ceramics Engineering
Discipline
Ceramics Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Materials Science
Abstract
CdGeAs(,2) is a member of the II-IV-V chalcopyrite semiconductor family. The crystallization of the amorphous form of this compound was investigated using Differential Scanning Calorimetry. The basic operating principles of the two currently most popular DSC instruments (the DuPont 1090 DSC and the Perkin-Elmer DSC7) in the context of glass crystallization kinetics are critically evaluated and compared. New analytical methods are introduced for the determination of kinetic parameters of crystallization, modeling to the Avrami and Arrhenius equations; and techniques for optimization of quantitative data from these devices is discussed for both heating rate and isothermal crystallization.
The results of X-ray diffraction, DSC, and TEM experiments indicate the nucleation and restricted growth of a precursor crystalline phase just prior to the formation of chalcopyrite structured CdGsAs(,2), which is then postulated to convert chalcopyrite late in the transformation. The precursor crystalline phase is believed to be germanium doped with trace amounts of cadmium and/or arsenic. A hypothesis is proposed using this precursor phase to explain certain observed devitrified microstructures.
Methods of calculating melt quench rates, laser surface crystallization, and a SEM nucleation study, are briefly outlined.
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