Na Diffusion and Device Performance of AgBr Treated CuGaSe2 Thin Films

Previous work demonstrated that uniform CuGaSe 2 (CGS) thin films with large grains could be grown using a short AgBr vapor treatment during growth. Devices made with this treated CGS showed better performance compared to devices made with standard material. Here, it is shown that AgBr treated CGS device performance worsens over time and is attributed to the suppression of N a diffusion. A NaF post-deposition treatment is shown to effectively introduce N a into the AgBr treated CGS film and prevent device degradation.