Comparative Study of Cu₂Te and Cu Back Contact in CdS/CdTe Solar Cell

In CdS/CdTe solar cells, Cu is added during the formation of the metallic electrode to enhance the contact properties and achieve an appropriate hole concentration in the cadmium telluride (CdTe) layer. In this study, we added Cu to CdS/CdTe solar cells using two different electrode materials: metallic Cu and Cu₂Te layers. They were deposited on the CdTe surface in the CdS/CdTe solar cells, and subsequent annealing was carried out to form a single-phase copper telluride compound. The devices made by these two materials were comparatively investigated in terms of their contact properties such as barrier height, hole density, and contact resistance. Most of the data indicate that the Cu₂Te-deposited cell is superior to the Cu-deposited cell. Furthermore, we obtained an optimum annealing condition for the Cu₂Te process, at which the cell performance is maximized. These results demonstrate the excellence of the Cu₂Te material and provide practical information about the processing technique of this material.