WSE2 THIN-FILM REALIZATION BY SYNTHESIS AND BY TARNISHING

Thin W films were deposited by RF sputtering onto a glass substrate an d then covered with an Se layer. The WSe2 layers were obtained either by annealing the W layers in a vacuum sealed Pyrex tube or by the tarn ishing reaction of Se vapour on W films. The properties of the thin WS e2 films made by synthesis and by tarnishing are described. The layers were examined by x-ray diffraction, x-ray photoelectron spectroscopy, scanning and transmission electron microscopy, electron microprobe an alysis, optical transmission and resistivity measurements. The films c rystallize in the hexagonal structure. It has been found that stoichio metric layers are obtained after synthesis while layers obtained by ta rnishing are partly oxidized. The optical gap of the synthesized layer s is in good agreement with the expected value. The electrical resista nce is governed by grain boundary scattering mechanisms.