Laser processing of copper sulfide thin film prepared by spray pyrolysis

Copper sulfide (Cu2S) thin films were deposited by spray pyrolysis technique on glass substrate at 370 °C from aqueous solutions of copper chloride dehydrate (CuCl2.2H2O) and thiourea (SC(NH2)2). The sprayed film was blackish brown in color, well adhered to the substrate, pin-hole free and uniformly distributed. The film was treated by a laser beam of 805 nm. The structural, surface morphological, optical and electrical properties of the films were measured, before and after laser treatment, by means of X-ray diffraction, scanning electron microscopy SEM, EDAX, optical transmittance and reflectance and two point probe technique. XRD showed close structure of copper rich phase (chalcocite, Cu2S) for both as-deposited and laser treated films. Laser treated film showed an increment in the crystallite size, proved by XRD and SEM image. It also showed a red shift in the optical band gap calculations, as well as, a higher electrical conductivity. The electrical conductivity of the sprayed Cu2S films depends on the stoichiometry in the films. Both as-deposited and laser treated films showed highly absorber coefficient which may have the potential as absorber layer in solid state solar cells.