Study on two-step process of preparing CIGS films

The method of "selenization of stack element layers" to prepare CIGS films was studied in this article. Cu-Ga and In metallic layers were deposited alternatively by magnetic sputtering, which was followed by selenization(450 °C) and annealing(550 °C). The SEM showed that CIGS film appeared smooth and compact when the precursors were sputtered at low substrate temperature and with a sequence of Mo/Cu-Ga/In/Cu-Ga/In. After selenization, the bi-layer film was attained from the SEM pictures. The XRD indicated that double layers were composed of CIS on the top and CGS on the bottom. Moreover, the separate CIS and CGS phases came to the homogeneous CIGS phase if an annealing process in inert atmosphere without selenium was introduced after selenization. Based on these improvements, the CIGS solar cell got a conversion efficiency of 7.5%.