Growth and morphology of Te films on Mo

Tellurium films were deposited by thermal evaporation on a molybdenum subst rate held at 120 degrees C. The growth of the films was monitored by quanti tative X-ray photoelectron spectroscopy and by atomic force microscopy. Rea ction of the Te films with K vapour was also used to evaluate the thickness of the films. It has been found that for low exposures Te grows as a unifo rm layer, up to a thickness of about 0.4 nm. For higher exposures we observ ed the formation of islands of increasing thickness that cover an increasin g fraction of the substrate, the remaining fraction being covered by a cont inuous thin layer. Implications of such a morphology on the performances of Te-based photocathodes in photo-injectors technology are discussed. (C) 19 99 Elsevier Science S.A. All rights reserved.