The relationships between electronic properties and microstructure of Cu(In,Ga)Se₂ films prepared by sputtering from a quaternary target

In this work, copper indium gallium selenide (CIGS) absorbers were prepared by sputtering a CIGS quaternary target followed by a subsequent annealing process. The electronic properties and microstructure of the CIGS films with various annealing time were investigated. The various annealing time changes the content of the Cu-Se compounds. A high Cu-Se content leads to a high carrier concentration and a low mobility. An improved efficiency of the solar cell device was found to be highly correlated with the decrease of the Cu-Se content. By decreasing the Cu-Se content, a device with a highest efficiency of 8.63% was achieved in this work.