Ga distribution and adhesion issues in selenization of metallic Cu-Ga-In precursors

A Three-step selenization process consisting of H₂Se/Ar/H₂Se reaction was employed to mitigate adhesion and Ga homogeneity problems in the formation of Cu(InGa)Se₂ films. In particular, reaction conditions for the 3rd step have been experimentally optimized to address these issues. The Cu(InGa)Se₂ films prepared by three-step selenization using H₂Se/Ar/H₂Se sequentially at 400/550/500°C with the reaction times of 30/20/(20-30) min had good adhesion to Mo and survived the chemical bath deposition of CdS. Additionally, EDS, XRD and AES analyses show significantly improved Ga homogeneity through the depth of the film. However, AES results indicate Ga depletion near the surface where it matters, also evidenced by low VOC in J-V plot.