Growth of zinc sulfide thin films with the successive ionic layer adsorption and reaction method as studied by atomic force microscopy

Abstract

Zinc sulfide thin films have been grown on soda-lime glass and mica substrates using the successive ionic layer adsorption and reaction (SILAR) technique. The film growth was studied by atomic force microscopy (AFM). Both in situ and ex situ techniques were utilized to examine the very first steps of the film growth. The thicker films were examined ex situ only. The investigations were focused on the growth mechanism (i.e. nucleation, formation of agglomerates and the growth mode) as well as on the roughness development of the films. During the growth process the thin films first showed a two-dimensional, then a three-dimensional and finally again a two-dimensional growth mode. The changes in growth mode had a large influence on the roughness of the film. The maximum root-meansquare (rms) roughness measured was 23 nm after 200 cycles of film deposition, but ultimately a smooth, continuous ZnS thin film with an rms roughness of ca. 6 nm was achieved.