1：Experimental Design and Method Selection:

Cu-poor CIGS films were grown at substrate temperature of 350 °C using a single stage process. Post-growth recrystallization was performed by annealing them at 550 °C for 30 min inside the deposition chamber using Se or NaF, KF, RbF and CsF under Se pressure.

2：Sample Selection and Data Sources:

The samples were grown on molybdenum-coated silicon substrates to isolate the effect of alkali diffusion from the substrate.

3：List of Experimental Equipment and Materials:

Thermal evaporation for deposition, separate evaporation source for alkali fluoride, X-Ray Fluorescence (XRF), scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS), X-ray diffraction (XRD), spectroscopic ellipsometry (SE), Hall-effect measurements.

4：Experimental Procedures and Operational Workflow:

The growth rate for deposition of the CIGS layer was 10 μm/h. Anneals were done using Se or NaF, KF, RbF and CsF under Se pressure. The alkali fluoride was provided during the anneal by a separate evaporation source at a rate of

5：4 ?/s, resulting in 70 nm deposition. Data Analysis Methods:

The elemental composition of the films was determined by XRF, the film morphology was examined by SEM, the elemental composition profile was analyzed by SIMS, structural analysis was by XRD, and the optical and electrical properties were extracted using SE and Hall-effect measurements, respectively.