NOVELTY - Electrodepositing Group IIIA material rich thin film involves electrodepositing interlayer over surface (36) of base (30), where interlayer having In or Ga, and at least Cu, Se, Te, Ag or S; and electrodepositing Group IIIA material rich thin film on interlayer to thickness, where the Group IIIA material rich thin film is one pure In film, Ga film and In-Ga alloy.    USE - For electrodepositing Group IIIA material rich thin film over a surface of a base used for manufacturing solar cell precursors. Where thin films are used in fabrication of semiconductor and electronic devices such as thin film solar cells.    ADVANTAGE - The electrochemical deposition method forms uniform and continuous Group IIIA material rich thin films.    DETAILED DESCRIPTION - Electrodepositing a Group IIIA material rich thin film over a surface of a base involves electrodepositing an interlayer over the surface (36) of the base (30), where the interlayer having a predetermined molar percent of at least one In and Ga, and at least 10 molar percent of additive material including one of Cu, Se, Te, Ag and S, where the predetermined molar percent is in the range of 20-90 percent; and electrodepositing the Group IIIA material rich thin film on the interlayer to a predetermined thickness, where the Group IIIA material rich thin film is one of a substantially pure In film, a substantially pure Ga film and In-Ga alloy, where the predetermined thickness of the Group IIIA material rich thin film is less than 700 nm, and where the thickness of the interlayer is less less than or equal to 20% of the predetermined thickness. The interlayer comprises In (40-80 molar%), and the balance at least one of Cu and Te. The method further involves forming a first layer on the surface of the base before electrodepositing the interlayer, where the first layer includes at least one of Cu and Ga. An INDEPENDENT CLAIM is included for a precursor layer structure for forming a Group IBIIIA VIA solar cell absorber comprising a conductive base layer; an interlayer formed over the conductive base layer; and a Group IIIA material rich thin film formed on the interlayer layer to a predetermined thickness.    DESCRIPTION OF DRAWING(S) - The figure shows cross-sectional view of structure formed by electroplating a sub-micron thick In layer on a sub-layer.    Base (30)    Substrate (31)    Contact layer (32)    Under layer (33)    Surface (36)