Effect of metallic precursors on the thin film thickness and reaction resistances in the selenization process

In the selenization process, the sputtered metallic precursors transformed into CIGS thin films, which were investigated by novel in-situ resistance measurement. Simultaneously, the crystal phases and thicknesses of the selenized thin films at various selenization temperatures are obtained by XRD and XRF, respectively. According to the analysis of phase evolutions and reaction characteristics, it can be confirmed metallic In existed in the precursors will transform into the In–Se compound directly and then results in CIS formation as well as the thickness increase below 370 °C. Otherwise, if alloy phases Cu–In and Cu–Ga co-exist in the precursors, not CIS but CIGS will form above 470°, which will lead to both thickness and resistance increase in the corresponding temperature range. Consequently, it can be concluded the thickness increase are decided by the formation of CIS or CIGS, whereas the strong reaction peak in the temperature-resistance curves are caused only by stoichiometric CIGS.