Properties of AgInS2 films prepared by spray pyrolysis for solar cells

The authors have prepared AgInS₂ thin films by the spray pyrolysis technique. The effects of the growth temperature and the chemical composition of the solution upon the structural, the optical and the electrical properties of the films have been studied. It was found that growth temperatures above 400°C lead to single-phase chalcopyrite type AgInS₂ films, but deposition temperatures lower than 400°C lead to mixed chalcopyrite and orthorombic structure films. All the films grown here show n-type conductivity with room temperature resistivities in the range between 10³-10 ⁵ Ω-cm. The absorbance derivative spectra of single phase AgInS₂ films revealed two energy gaps around 1.87 eV and 2.03 eV, attributed to the fundamental edge and to the valence band splitting by the crystal-field, respectively