NOVELTY - The method comprises: forming a first metal precursor film above a surface of a substrate, where the first metal precursor film comprises copper (Cu), indium (In) and gallium (Ga); converting a portion of the first metal precursor film to a chalcogenide film through heating the first metal precursor film in the presence of a chalcogen at a temperature of 100-700 degrees C during a first converting step in a reaction chamber; and forming a second layer above the first metal precursor film, where the second layer comprises aluminum (Al) and is formed while the substrate is formed within the chamber.    USE - The method is useful for forming a semiconductor material on a substrate (claimed) for fabricating thin film photovoltaic (PV) device including a solar cell or a panel, which is useful in commercial markets including residential rooftops, commercial rooftops, utility-scale PV projects, building integrated PV, building applied PV, electronic devices and clothing.    ADVANTAGE - The method allows economical formation of the semiconductor material with high density and quality in an environment-friendly manner thus enhancing performance, conversion efficiency, power production and reliability of the photovoltaic device.    DETAILED DESCRIPTION - The method comprises: forming a first metal precursor film above a surface of a substrate, where the first metal precursor film comprises copper (Cu), indium (In) and gallium (Ga); converting a portion of the first metal precursor film to a chalcogenide film through heating the first metal precursor film in the presence of a chalcogen at a temperature of 100-700 degrees C during a first converting step in a reaction chamber; forming a second layer above the first metal precursor film, where the second layer comprises aluminum (Al) and is formed while the substrate is formed within the chamber; and converting the first metal precursor film and the second layer to a chalcogenide film through heating the first metal precursor film and the second layer in the presence of the chalcogen at a temperature of 100-700 degrees C during a second converting step within the reaction chamber. The method further comprises annealing the substrate after the second converting step.    DESCRIPTION OF DRAWING(S) - The diagram shows a flow diagram for forming a semiconductor material on a substrate.    Depositing multi-component metal film (1102)    Partially or fully chalcogenizing the multi-component film (1104)    Depositing group-IIIA-rich film (1106)    Fully converting the film into a chalcogenide film (1108)    Annealing the chalcogenide film. (1110)