THERMALLY-INDUCED PROCESSES IN THIN-LAYERS, OBTAINED BY COEVAPORATIONOF TEO2 AND SN

Thin layers with controlled Sn/Te ratio (0 divided by 2) and thickness are prepared by coevaporation of TeO2 and Sn. The structure and chemi cal composition of the as-deposited layers and the changes they underg o upon heating are studied by various transmission electron microscopy techniques and energy dispersive spectroscopic and electron spectrosc opy for chemical analysis. It is shown that during the coevaporation a chemical reaction between TeO2 and Sn takes place resulting in the pr oduction of a finely dispersed phase of elemental Te. Upon annealing t ransport of the dispersed elemental Te to the free upper surface of th e layer, particle growth and crystallization are observed. A strong co rrelation between the concentration of elemental Te in the layer and t he rate of these processes is found. The reaction between TeO2 and Sn proceeds till the complete consumption of TeO2 or Sn; SnTe is formed o nly at excess amounts of Sn and after all TeO2 is consumed. (C) 1998 A merican Vacuum Society. [S0734-2101(98)02504-4].