The formation of ZnTe:Cu and CuxTe double layer back contacts for CdTe solar cells

Processes to form a CuxTe layer on a ZnTe:Cu layer were investigated by various deposition methods and heat treatment. These were to make ZnTe:Cu/CuxTe double layer contacts for CdTe solar cells and to have benefit from both the well-matched interfacial property of ZnTe:Cu and low-resistivity CuxTe. The method to form CuxTe compounds was annealing the bi-layer of copper and tellurium which were deposited by sputtering. At an adequate annealing condition, CuxTe alloy was formed while maintaining underlying ZnTe without intermixing. CuxTe was also formed using co-deposition method. However, in terms of crystallinity, the bi-layer deposition method was considered to be better. According to this experiments, ZnTe:Cu/CuxTe double layer contact was successfully formed. This double layer contact is expected to be a good candidate for high efficiency CdTe solar cell.