Structural and electrical properties of co-evaporated In,Garich CIGS thin films

The CIGS thin films are prepared by co-evaporation of elemental In, Ga and Se on the substrates of Mo-coated glasses at 400°C followed by co-evaporation of elemental Cu and Se at 550°C. We study the structural and electrical properties using XRD, XRF and Hall effect measurements. In general, Cu(In,Ga)₅Se₈ phase exists when Cu/(In+Ga) ratio is from 0.17 to 0.27, Cu(In,Ga)₃Se₅ phase exists for Cu/(In+Ga) ratio between 0.27 and 0.41, Cu₂(In,Ga)₄Se₇ and Cu(In,Ga)₂Se_3.5 phases exist for Cu/(In+Ga) ratio between 0.41 and 0.61, and OVC(or ODC) and CuIn_0.7Ga_0.3Se₂ phases exist when Cu/(In+Ga) ratio is from 0.61 to 0.88. With the increase of Cu/(In+Ga) ratio, the carrier concentrations of the films gradually increase, but the electrical resistivity gradually decreases.