CRYSTALLIZATION BEHAVIOR OF AMORPHOUS GE-(1-X)SB-X THIN-FILMS

The crystallization behaviour of amorphous Ge1-xSbx thin films, deposited by sputtering, at three compositions: x = 0.68, 0.73 and 0.84 have been studied. The crystallization has been induced by annealing in vacuum and monitored by optical absorption. Samples have been characterized by X-ray diffraction , energy-dispersive X-ray and transmission electron microscopy. The crystallization temperature, Theta(c), is composition-dependent and decreases with Sb content. In the crystallization process, three composition intervals can be distinguished. At high Ge content, x less than or equal to 0.6, crystallization leads to two separated phases, c-Ge and c-Sb. At x similar or equal to 0.68 Sb crystallizes in a first step followed by Ge crystallization At x greater than or equal to 0.73, only Sb crystallizes and for the eutectic composition, x = 0.84, Sb crystallizes with [0 0 1] zone axis perpendicular to the film surface as found in pure Sb films.