Attempting Doping Activation via Rapid Thermal Annealing in As-Doped Polycrystalline CdSeTe Solar Cells

Doping the absorber layer is a critical process for enhancing the performance of polycrystalline CdSeTe solar cells. Replacing traditional Cu doping with Group V dopants offers a pathway to fabricate devices with improved efficiency and stability. However, the dopant activation rate in polycrystalline structures remains low, typically only a few percent. While rapid thermal annealing (RTA) has been successfully employed to achieve high activation rates in single-crystal CdTe devices, its application to polycrystalline CdSeTe solar cells has been scarcely reported. In this study, we systematically applied multi-step annealing to investigate the dopant activation of in-situ As-doped polycrystalline CdSeTe devices. Our findings reveal that polycrystalline devices exhibit significantly lower thermal tolerance than their single-crystal counterparts, sustaining only short-duration annealing at 500°C. Furthermore, although Cl diffusion during RTA can degrade device performance, we observed that trace amounts of CdCl2 vapor can help stabilize device efficiency.