NOVELTY - Manufacturing solar cell involves depositing first electrode comprising alkali-containing transition metal layer over substrate (100) by sputtering from first target having transition metal (27a, 17b) and second target containing alkali metal (37a, 37b); depositing p-type semiconductor absorber layer over first electrode, where p-type semiconductor layer includes copper indium selenide (CIS) based alloy material; depositing n-type semiconductor layer over the p-type semiconductor layer; and depositing second electrode over n-type semiconductor layer.    USE - For manufacturing solar cell (claimed).    ADVANTAGE - The small amount of sodium dopants in CIS films increases the p-type conductivity of the copper indium gallium diselenide (CIGS) film and the open circuit voltage, thus improves the efficiency of the solar cell. The alkali-containing transition metal layer provides an alkali source that may be controllably diffused to the CIS based layer. The metal selenide interfacial layer improves the adhesion and provides a good ohmic contact between the alkali-containing transition metal layer and the CIS based layer.    DETAILED DESCRIPTION - Manufacturing solar cell involves depositing first electrode comprising alkali-containing transition metal layer over substrate (100) by sputtering from first target having transition metal (27a, 17b) and second target containing alkali metal (37a, 37b); depositing p-type semiconductor absorber layer over first electrode, where p-type semiconductor layer includes copper indium selenide (CIS) based alloy material; depositing n-type semiconductor layer over the p-type semiconductor layer; and depositing second electrode over n-type semiconductor layer. Alternatively, manufacturing solar cell involves depositing transparent electrode over substrate; depositing n-type semiconductor layer over the transparent electrode; depositing p-type semiconductor absorber layer over n-type semiconductor layer; and depositing top electrode comprising alkali-containing transition metal layer over p-type semiconductor absorber layer.    DESCRIPTION OF DRAWING(S) - The figure shows a highly simplified schematic diagram of a top view of a sputtering apparatus.    Transition metal target (27a, 17b)    Alkali metal target (37a, 37b)    Substrate (100)