Crystal growth and characterization of I-IV2-V3 semiconductor compounds and alloys based thereon.

  • Mustafa Saeed Omar

Student thesis: Doctoral ThesisPhD

Abstract

The existence of various ternary adamantine compounds is discussed. Normal and defect ternary adamantine compounds have been a subject of discussion, particularly from a structural point of view. Rules for the formation of adamantine compounds are explained and related to each other. A home-made DTA apparatus was operated to detect the melting point and phase change from room temperature up to 1300°C for the materials investigated. The group I-IV2-V3 compounds were the main subject of this research. CuGe2Ps and CuSi2P3 were the only compounds found to grow in this family. The first was chosen for study in more detail, mainly because of its lower melting point. CuGe2P3 was compared to other compounds, particularly structural aspects, and solid solutions were tried for twenty-two different materials. This investigation shows similarity with group I2-IV-V3 compounds, such as Cu2GeS3, and new alloys were found with Cu2GeS3. Stoichiometric Cu2GeS3 does not form good material, but alloys containing 10% CuGe2P3 produced good material with a zincblend structure. As well as alloys with ternary compounds, about 33% Ge per mole could be dissolved in CuGe2P3. This result showed similarity with the compounds Cu2GeSe3 and ZnGeAs2, which also dissolve a considerable quantity of Ge. In this investigation, only a maximum of 33% Si per mole in CuSi2P3 was prepared, although it is likely that even more Si can be dissolved. Attention was also given to AqGe2P3. Chemical analysis of single crystals grown from AgGe2P3 composition showed the existence of only the Ag6Ge10P12 compound. Single crystals were grown for all single phase materials. A new modification of the directional freeze technique was employed, which was capable of controlling the pressure and having a steep temperature gradient. This method improved the growth to produce large single crystals of cm dimensions. The CuGe2P3 crystals doped with Zn, S, Sn, Se and ZnIn were prepared. Single crystals of CuGe2P3 were also annealed with Cu-P and CuGe2P3 powder. Room temperature lattice parameters were determined for all the compounds and alloys, while variations of the lattice parameters with temperatures up to the melting point of CuGe2P3 were studied using a high temperature X-ray camera. Measurements of optical properties were not successful in this investigation, although electrical properties were successfully measured. These measurements were carried out for all materials in a single crystal form. Hall mobility and conductivity measurements were carried out from liquid nitrogen to 450 °K. Carrier concentration was very high for phosphide compounds and alloys, whilst it was lower for sulphides. Flash evaporation was used for preparing thin films of compounds CuGe2P3 and Ag6Ge10P12. Single phase films were the result for Ag6Ge10P12, whilst a particular treatment was employed for producing films of CuGe2P3 after evaporation. A final investigation of the compound CuGe2P3 was made into its lattice matching with other compounds. The p-n junctions were produced with n-type GaP, using epitaxial growth, while results were negative with CdS and Si.
Date of Award1985
LanguageEnglish
Awarding Institution
  • University of Bath

Cite this

Crystal growth and characterization of I-IV2-V3 semiconductor compounds and alloys based thereon.
Omar, M. S. (Author). 1985

Student thesis: Doctoral ThesisPhD