Preparation and characterization of patterned copper sulfide thin films on n-type TiO2 film surfaces

Micro-arrayed patterns of p-type copper sulfide (CuxS) thin films with positive and negative features were deposited onto the surfaces of n-type TiO2 semiconductor films via a selective nucleation and growth process from aqueous solution. The surface functional molecules of the UV photo-oxidised patterned SAMs were utilized to direct the nucleation and growth of CuxS crystallites. The resultant CuxS/TiO2 composite films with negative and positive CuxS patterns on the TiO2 film surface were investigated using SEM, XRD, XPS and a 3D Surface Profiler. It is demonstrated that regular and compact patterned films of Cu2S crystallites had been deposited onto the n-type TiO2 surface, with sharp edges demarcating the boundaries between the patterned Cu2S region and the TiO2 film region. The UV–vis spectra for three Cu2S/TiO2 films exhibit a wide absorption between 300 nm and 450 nm. The maximum wavelength differences in the spectra of Cu2S/TiO2 films and TiO2 film were attributed to the added absorption of Cu2S films at 302 nm and the unchanged adsorption of TiO2 films. The absorption intensities of the Cu2S/TiO2 films could be varied in the UV–vis range using the Cu2S patterned features (positive, negative).