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

The specific contact resistivity (ρC) for aluminum (Al), silver (Ag) and indium (In) metallic contacts on CuInS2 thin films was determined from I–V measurements, with the purpose of having the most appropriate ohmic contact for TCO/CdS/CuInS2 solar cells; ρC was measured using the transmission line method (TLM) 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 ρC values for CuInS2 samples grown with x=1.5. The minimum ρC was 0.26 Ω cm2 for the In contacts. This value, although not very low, will allow the fabrication of CuInS2 solar cells with a small series resistance.