Characterization of CuInSe2 thin films grown by photo-assisted electrodeposition

A photo-assisted one-step electrodeposition has been applied to help in forming smooth and dense CuInSe2 (CIS) films. The difference in surface morphology and crystalline quality between CIS films with and without photo-assistance has been investigated. In the photo-assisted electrodeposition process, a halogen lamp providing maximum light intensity at about 0.6 μm–1.0 μm was used as light source to be irradiated onto the surface of Mo-coated soda lime glass substrates. Electrodeposited CIS thin films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM) and Raman spectroscopy. SEM and AFM results show a smoother film with lower roughness by photo-assisted electrodeposition at lower deposition potential. From the XRD patterns, it was found that photo-assistance enhanced the crystalline quality, and the enhancement remained after annealing at 500 °C for 120 s. The analysis of Raman spectra indicated a reduction in secondary phases after applying photo-assistance. These results suggested effects of photo-assistance including activating surface diffusion and growing high-crystalline quality films with reduced defects during electrodeposition.

► A photo-assisted electrodeposition process is proposed.
► Dense CuInSe2 films with lower roughness are achieved by photo-assistance.
► Better crystallinity is achieved by photo-assistance.
► Secondary phases in CuInSe2 thin films are reduced by photo-assistance.