IN-SITU TEM OBSERVATION OF NICKEL PROMOTED WS2 THIN-FILM CRYSTALLIZATION

In the present study, the crystallization of amorphous Ni/WS3+X (0 < X < 2) thin films is observed in real time during an in situ annealing of the thin-film samples in a transmission electron microscope. The ob tained results make possible for the first time the development of a c onsistent growth model for promoted WS2 thin-him growth. In this model , the nickel film reacts with the excess sulfur in the amorphous WS3+X film to form large NiSX drops, which are liquid at the annealing temp erature of 800 degrees C. Small WSI crystallites, which are in contact with the liquid nickel sulfide phase, are dissolved in the melt. At t he same time, large WS2 crystallites grow laterally from this saturate d solution. (C) 1998 Elsevier Science B.V. All rights reserved.