Study Of The Effects Of Non-Vacuum Deposited Alkali-Metals On Copper-Indium-Gallium-Selenide Absorber Layers For Solar Cells

In this study, we carried out surface post-deposition treatment (PDT) on the CIGSe layer with heavier alkali metals using a non-vacuum method. X-ray diffraction studies confirmed that no secondary phases forms after the PDT. Morphological studies using scanning electron microscopy showed the presence of some enlarged grains after PDT with a substantial increase in mobility from Hall effect measurements. Further topographical characterization using atomic force microscopy (AFM) shows a reduction in peak-to-peak surface morphology due to the PDT. The comparison of the bandgap values after PDT showed a slight variation due to variation in the In/Ga ratios. The Raman spectroscopy of all the samples exhibited only the A1 characteristic mode of the chalcopyrite structures with a shoulder attributed to the presence of ordered vacancy layers (OVC) formed by the alkali metal secondary phases.