NOVELTY - Group IB-IIIA-VIA or Group IIB-IVA-VA compound film is formed by preparing source material including particles containing Group IB element and Group IIIA element or Group IIB element and Group IVA element in oxide form; depositing the source material on base and forming preparatory film; heating the preparatory film in an atmosphere that provides oxide reduction to form precursor film; and providing material to the precursor film to form a film including a compound comprised of Group IB-IIIA-VIA compound or Group IIB-IVA-VA compound.    USE - For formation of Group IB-IIIA-VIA or Group IIB-IVA-VA compound film used for solar cells and electronic device.    ADVANTAGE - The method makes use of techniques to provide Group IB-IIIA-VIA and related compound films on large area substrates, with good composition control and uniformity. The resulting compound films exhibit superior electronic properties.    DETAILED DESCRIPTION - The formation of Group IB-IIIA-VIA or Group IIB-IVA-VA compound film comprises:    (A) preparing source material including particles containing Group IB element and Group IIIA element in oxide from, for the Group IB-IIIA-VIA compound film, or Group IIB element and Group IVA element in oxide form, for the Group IIB-IVA-VA compound film;    (B) depositing the source material on a base and forming a preparatory film from the source material;    (C) heating the preparatory film in an atmosphere that provides oxide reduction to form precursor film including non-oxides of Group IB and IIA elements or non-oxides of Group IIB and IVA elements, in which the atmosphere does not contain any of the Group VIA elements and any of the Group VA elements; and    (D) providing material to the precursor film to form a film including a compound comprised of Group IB-IIIA-VIA compound or Group IIB-IVA-VA compound, in which for the Group IB-IIIA-VIA compound a Group VIA source is provided, and for the Group IIB-IVA- VA compound a Group VA source is provided, from a gaseous atmosphere with heating or by deposition with heating.    A ratio by number of moles of Group IB to Group IIIA elements in the source material is 0.6-1. The oxides constitute greater than 95 mol.% of the Group IB elements and greater than 95 mol.% of the Group IIIA elements in the source material. The non-oxides constitute greater than 95 mol.% of the Group IB elements and greater than 95 mol.% of the Group IIIA elements in the precursor film. Preparing the source material comprises providing a powder including particles containing oxides of Group IB and IIIA elements; and forming an ink including particles containing oxides of Group IB and IIIA elements. The particles contain copper from Group IB and Group IIIA material comprised of indium or gallium. The precursor film includes an alloy of Group IB and Group IIIA elements. The source material includes dopant comprised of sodium, potassium, lithium, or cerium. INDEPENDENT CLAIMS are included for:    (1) a method for fabricating an electronic device including the method for forming the compound film; and    (2) a method for fabricating a solar cell including the method for forming the compound film as an absorber layer.    DESCRIPTION OF DRAWING(S) - The figure is a flow chart showing steps for growing compound semiconductor films, including 3 groups of elements.