Stress and surface studies of SILAR grown ZnS thin films on (100)GaAs substrates

Zinc sulfide thin films were grown on (100)GaAs by the successive ionic layer adsorption and reaction (SILAR) technique from dilute aqueous precursor solutions. The stress of thin films was characterized by means of laser interferometry, crystallinity by X-ray diffraction, refractive index by ellipsometry and by fitting the reflectance spectrum, composition by electron spectroscopy and morphology by atomic force microscopy. A clear correlation between the growth mode and the residual stress level is demonstrated. The changes from three-dimensional to two-dimensional growth of the film results in the change of the residual stress from tensile to compressive. The films were polycrystalline and cubic with rather low crystallinity. The crystallite size and the refractive index of the films increased when the film thickness increased.