Electrical characterization of Al, Ag and In contacts on CuInS2 thin films deposited by spray pyrolysis

The specific contact resistivity (rho_C) for Aluminum (Al), Silver (Ag) and Indium (In) metallic contacts on CuInS₂ thin films have been determined, from I - V measurements, with the purpose of having the most appropriate ohmic contact for TCO/CdS/CuInS₂ solar cells. rho_C was measured using the transmission line (TLM) method for the metallic contacts evaporated on CuInS₂ thin films deposited by spray pyrolysis with ratios x = [Cu] / [In] = 1.0, 1.1, 1.3 and 1.5 in the spray solution. The results show that In contacts have the lowest rho_C values for CuInS₂ samples grown with x = 1.5. The minimum rho_C was 0.26 ohm-cm² for the In contacts. This value, although not very low, will allow the fabrication of CuInS₂ solar cells with a small series resistance.