Growth and characterization of CuGa_xIn_1-xSe₂ thin films for solar cells

CuGa_xIn_1-xSe₂ thin films have been prepared by using two different methods, that is: the direct evaporation of the compound and the flash evaporation. The best results have been obtained by using the second method. Thin films, whose forbidden gap is almost equal to that of the corrisponding single crystal with a resistivity of about 10 ω · cm or less and a hole mobility of about 1 cm² V^-1 sec^-1, were easily obtained by the flash evaporation method. The films exhibit a dark colour with very smooth surfaces. Finally, we prepared an heterojunction by depositing a CuGa_xIn_1-xSe₂ compound, in which the x value is 0.7, on an Al-doped ZnSe single crystal. For this heterojunction the lattice mismatch is near zero.