Effects of Se flux on the properties of the quaternary-sputtered CIGS thin film solar cells

Sputtering from a single CIGS compound target is a promising process to fabricate CIGS absorbers for mass production. However, only few reports demonstrate efficient CIGS cells without post-selenization. The need for the additional post-selenization step may be possibly due to the low Se supply during deposition, which originates from the low Se content in the target. In this study, we proposed a method to supply extra Se, sputtering from a Se target. With this, the Se supply during the quaternary sputtering process is adjusted nominally from 1 to 1.24. The effects of Se supply during the quaternary sputtering process on the film and device properties were studied. Efficiency of 11% was obtained with medium Se flux.