STUDY OF SURFACE PROPERTIES OF ATOMICALLY-CLEAN METALS AND SEMICONDUCTORS.
Progress rept. no. 4, 1 June-31 Dec 63,
BARUS RESEARCH LAB OF PHYSICS BROWN UNIV PROVIDENCE R I
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The 0001 Surfaces of CdS were examined by means of Low-Energy Electron Diffraction. Heating the CdS crystal in oxygen at 200C induces adsorption on the 0001 SPECULAR surface. The 0001 MATTE surface of a high purity CdS crystal was ex amined. The results for this crystal showed the presence of surface planes in agreement with the results for the same face of another CdS crystal whose purity was unknown. The 0001 MATTE surface of a high purity CdS crystal was prepared for examination without chemical etch and without exposure to temperatures higher than 400C. A weak diffraction pattern characteristic of diffraction from a 0001 plane and containing half integral as well as integral order beams in two major azimuths was obtained in agreement with the results for the 0001 SPECULAR surface. These results show that the chemical etch exposes the planes on the MATTE surface. Heating the crystal near 500C in a vacuum caused the appearance of planes as in the case of the chemical etch. Thus the plane on the MATTE surface is unstable under the conditions of chemical etch or heat treatment near 500C in a vacuum. Author