EFFECTS OF HEAT CLEANING ON THE PHOTOEMISSION PROPERTIES OF GaAs SURFACES

Abstract

Heat cleaning in ultrahigh vacuum, when carried out properly on practical GaAs surfaces, has achieved very high quantum efficiency (∼600 μA/lumen) after activation with Cs and O₂. This is better than 50% of the best UHV cleaved GaAs. The inherent limitations of heat cleaning are the possibilities of dopant out diffusion and loss of As. Our experiments are consistent with out diffusion of Zn at about 650°C, and a sufficiently small loss of As at this heating temperature so as to result in negligible As vacancies near the surface of the crystal