Effect of sodium dodecyl sulfate on surface roughness and nucleation mechanisms of electrodeposited CuInSe₂ films

In this study, the p-type CuInSe₂ thin films were fabricated by using pulse electrodeposition with anionic surfactant sodium dodecyl sulfate (SDS) as an additive. The effect of the SDS on the surface roughness and the nucleation mechanisms of electrodeposited CuInSe₂ films have been investigated in detail. It was found that films fabricated in electrolyte containing SDS surfactant are smooth and compact compared to those fabricated in electrolyte without the SDS surfactant. AFM images show that the self-assembly of SDS molecules can form directional and oblique lines lying on the Mo surface. These oblique lines can form a monolayer to change the nucleation mechanisms of films from the instantaneous to the progressive mode. The vibration modes of the chalcopyrite structure and the identification of Cu_xSe secondary phases were examined by micro-Raman spectrometry, which showed a decrease in secondary phases when SDS concentration was increased from 0.3 mM to 5 mM.