Ga-grading profiles formed by incorporation of gallium into Cu(In1−xGax)Se2 absorber thin films

► CIGS thin films with Ga-grading profile were prepared by evaporation of GaxSe for incorporation of gallium. ► The process was found to have little effect on the film structure. ► No new impurity phases were detected. ► The proposed process was feasible for forming a 'notch' Ga-graded structure in CIGS thin films.