RESEARCH ON IMPROVED II-VI CRYSTALS.
Final technical rept. 8 Mar 65-7 May 68,
CLEVITE CORP CLEVELAND OHIO ELECTRONIC RESEARCH DIV
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This research program has been directed toward improving the quality of vapor-grown CdS, CdSe, and ZnTe crystals from the standpoint of both foreign impurities and intrinsic structural defects. Measurable improvements in purity of the final crystals have been obtained by specific purification steps, consisting of a sintering procedure and one or more fractional vacuum sublimations, applied to available semiconductor-grade material. Crystal quality as related to intrinsic defects has been improved, both during crystal growth and treatment after growth, through a better understanding of phase equilibria and point-defect equilibria and their relationships. A computer program has been set up and specific calculations were made for ZnTe. Evidence from diffusion experiments and from the examination of the void-precipitation phenomenon in ZnTe has shown that Zn vacancies are the significant intrinsic point defects in this material. Evaluation of crystal quality has primarily been placed on microscopic observations and electrical measurements such as photoconductivity, thermally-stimulated currents, and current oscillations.
- Solid State Physics