Band gap engineering of RF-sputtered CuInZnSe2 thin films for indium-reduced thin-film solar cell application

We demonstrated the preparation and characterization of radio frequency (RF)-sputtered CuInZnSe2 thin films for indium-reduced thin-film solar cell application. Sputtering targets composed of high-purity CuSe, InSe and ZnSe powders were employed for preparing CuInZnSe2 films with various band gaps. Under an optimum condition, an increase of zinc concentration in the film could reduce indium approximately to 45%. The structure of the films showed a chalcopyrite phase with a predominant (1 1 2) reflection. The p-type CuInZnSe2 films exhibited a shift of optical transmittance to a lower wavelength and the band gap could be engineered from 1.0 to 1.25 eV in proportion with increasing zinc concentration.