NOVELTY - Method (M1) for forming a semiconductor material on a substrate, comprises: (a) forming a first precursor film above a surface of the substrate; (b) converting at least a portion of the first precursor film to a chalcogenide film through heating the first precursor film in the presence of a chalcogen at 100-700 degrees C during a first converting step; (c) forming a second precursor film (s1) above the first precursor film after the first converting step; and (d) converting the first precursor film and the second precursor film (s1) to a chalcogenide material.    USE - The methods are useful for forming a semiconductor material on a substrate, which is useful in thin film solar cells (claimed).    ADVANTAGE - The methods: provide semiconductor material with high yield and improved performance; and are fast.    DETAILED DESCRIPTION - Method (M1) for forming a semiconductor material on a substrate, comprises: (a) forming a first precursor film above a surface of the substrate, where the first precursor film comprises copper, indium and gallium, and a copper composition (copper/(indium+gallium)) of the first precursor film is greater than 1; (b) converting at least a portion of the first precursor film to a chalcogenide film through heating the first precursor film in the presence of a chalcogen at 100-700 degrees C during a first converting step; (c) forming a second precursor film (s1) above the first precursor film after the first converting step, where the second precursor film (s1) comprises copper, indium and gallium, and a copper composition (copper/(indium+gallium)) of the second precursor film (s1) is less than 1; and (d) converting the first precursor film and the second precursor film (s1) to a chalcogenide material through heating the first precursor film and the second precursor film (s1) in the presence of a chalcogen at 100-700 degrees C during a second converting step. INDEPENDENT CLAIMS are also included for:    (1) a method (M2) for forming a semiconductor material on a substrate, comprising: (a1) forming a first precursor film above a surface of the substrate, where the first precursor film comprises copper, indium and gallium, and a copper composition (copper/(indium+gallium)) of the first precursor film is less than 1; the step (b) as above per se; (c1) forming a second precursor film (s1) above the first precursor film after the first converting step, where the second precursor film (s1) comprises copper, indium and gallium, and a copper composition (copper/(indium+gallium)) of the second precursor film (s1) is greater than 1; and the step (d) as above per se;    (2) a method (M3) for forming a semiconductor material on a substrate, comprising the steps (a1) and (b)-(d) as above per se;    (3) a method (M4) for forming a semiconductor material on a substrate, comprising: the steps (a) and (b) as above per se; removing excess copper-chalcogenide material from the first precursor film after the first converting step by exposing the first precursor film to a wet etch solution; and the steps (c) and (d) as above per se; and    (4) a method (M5) for forming a semiconductor material on a substrate, comprising: (a2) forming a first precursor film above a surface of the substrate, where the first precursor film comprises copper, indium and gallium; the step (b) as above per se; (c2) forming a second precursor film (s2) above the first precursor film after the first converting step, where the second precursor film (s2) comprises copper, silver, indium and gallium, and a gallium composition (gallium/(indium+gallium)) of the second precursor film (s2) is larger than 0.3; and the step (d) as above per se.