TRIGGERING OF DIFFUSION AND CRYSTALLIZATION OF AMORPHOUS-GERMANIUM INCONTACT WITH ANTIMONY

The diffusion and crystallization of amorphous Ge films in contact wit h Sb has been studied in bilayer Ge-Sb films. Under prolonged annealin g in vacuum, the Sb layer sublimes and, similarly to what happens unde r etching, the reactions which had occurred at the interface are 'reco rded' at the surface of the residual Ge film. The results show that th e bulk crystallization of the Ge layer occurs at 75% of the eutectic t emperature (in degrees Kelvin) of the Ge-Sb system although the trigge r of preferential diffusion and crystallization at the defects of the Sb grains is observed at lower temperatures. A comparison of the resul ts obtained in a-Ge films grown onto a Sb layer and films covered by a n Sb layer show that the interface in the former film configuration is more active than in the latter and leads to a different crystallizati on mechanism.