Sulfurization of sputtered Ag–In precursors for AgInS2 solar cell absorber layers

• AgInS2 films are grown by sulfurization of sputtered metal precursors.
• Effect of substrate temperature on the growth of AgInS2 films is studied.
• Films sulfurized at 500 °C have the best structural and opto-electrical properties.
• AgInS2/ZnS solar cell has been fabricated with an efficiency of ~ 0.3%.

Silver indium sulfide (AgInS2) thin films are deposited by sequential sputtering of metallic precursor [Ag/In] followed by sulfurization. Effect of substrate temperature (Tsub) during sulfurization process on the film growth is studied by varying the substrate temperature from 350 to 500 °C. Films prepared above 350 °C showed a mixture of orthorhombic and tetragonal phases of AgInS2 with tetragonal phase being dominant. Better crystalline, nearly stoichiometric and p-type films are obtained at a substrate temperature of 500 °C. The characteristic A1 mode of AgInS2 chalcopyrite structure is observed in the Raman spectra at 274 cm− 1 for the films prepared above 350 °C. The grain size of the film increases from 489 to 895 nm with the increase in substrate temperature. The binding energies of the constituent elements are determined using XPS. The band gap of AgInS2 films is in the range of 1.64–1.92 eV and the absorption coefficient is found to be > 104 cm− 1. Preliminary studies on the AgInS2/ZnS solar cell showed an efficiency of 0.3%.