Accession Number : AD0888289

Title :   Photoemission Studies of the Alkali Covered Germanium (111) Surface.

Descriptive Note : Technical rept.,

Corporate Author : MINNESOTA UNIV MINNEAPOLIS PHYSICAL ELECTRONICS LAB

Personal Author(s) : Riach, Gerald E.

Report Date : MAR 1971

Pagination or Media Count : 143

Abstract : Photoemission measurements were used to monitor changes in the surface potential of sputter annealed germanium (111) as a function of alkali coverage. Measurements included photoelectric yield and energy distributions and sample work function on the clean surface before and after the deposition, in controlled submonolayer amounts, of sodium and cesium using zeolite ion sources and a low energy ion gun. Changes in surface crystal structure were monitored using low energy electron diffraction. Results indicate that the clean surface is moderately p-type, becomes less p-type for alkali coverages below 0.03 monolayers, then becomes rapidly more p-type as coverage increases. Cesium coverage saturates at 0.5 monolayers and the surface is degenerately p-type. Strong evidence of photoemission from occupied surface states was observed for cesium coverages below 0.15 monolayers. In the case of sodium adsorption the surface is degenerately p-type from 0.5 monolayers to 0.9 monolayers but becomes nondegenerate as saturation is approached. Sodium saturation occurs at 1.25 monolayers. (Author)

Descriptors :   (*PHOTOELECTRIC MATERIALS, GERMANIUM), PHOTOELECTRIC EFFECT, SEMICONDUCTORS, CESIUM, WORK FUNCTIONS, PHOTOCATHODES, METAL FILMS, BAND THEORY OF SOLIDS.

Subject Categories : Miscellaneous Materials
      Solid State Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE