Analysis of contact reaction phenomenon between aluminum-silver and p+ diffused layer for n-type c-Si solar cell applications

Abstract

In this study, the contact mechanism between Ag-Al and Si and the change in contact resistance (Rc) were analyzed by varying the firing profile. The front electrode of an n-type c-Si solar cell was formed through a screen-printing process using Ag-Al paste. Rc was measured by varying the belt speed and peak temperature of the fast-firing furnace. Rc value of 6.98 mΩ-cm−2 was obtained for an optimal fast-firing profile with 865 ◦C peak temperature and 110 inches per min belt speed. The contact phenomenon and the influence of impurities between the front-electrode-Si interface and firing conditions were analyzed through scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The EDS analysis revealed that the peak firing temperature at 865 ◦C exhibited a low atomic weight percentage of Al (0.72 and 0.36%) because Al was involved in the formation of alloy of Si with the front electrode. Based on the optimal results, a solar cell with a conversion efficiency of 19.46% was obtained.