Analysis of the gallium gradient in Cu(In1-xGax)Se2 absorbers by X-ray diffraction

Abstract In order to analyze why the CIGS (CuInGaSe2) - based solar cells efficiency decrease for wide band gap (high Ga content), we have performed a series of samples by PVD using three stage process. The average compositions our range from x = 0 x = 0.88, as measured X-ray diffraction. An important feature this process is create double gradient into absorber, which contributes improve efficiencies, and has major impact on determination sample composition x-ray diffraction data. We developed model in assess question validity extracted This allows get some information about shapes. Using model, obtained insights evolution gallium with increasing content, determine that less pronounced when amount gallium. It well known fact assists extraction photocreated carriers, modifications profile determined may explain, part, degradation high compositions.