TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: In method (I), the depositing step comprises: preparing the compound bulk materials from the first and second chemical elements, forming at least one sputtering target from the compound bulk materials, and sputtering the compound bulk materials onto the substrate, or evaporating the bulk materials comprising the first and second chemical elements onto the substrate; and the inducing step of inducing includes exposing the film to a vapor that includes the second element. The residual chemical reaction: is produced at a temperature of at least 400 degrees C; and produces a film having a single crystalline phase. The second element content in the deposited film is increased by at least 10%. Preferred Components: The first and second chemical elements comprise many chemical elements, where the first chemical element comprises at least one element of Group I and Group III, and the second chemical element comprises an element of Group VI. The substrate comprises first contact layer. The second element composition is stoichiometric. The first chemical composition comprises: copper, indium, gallium and selenium; or cadmium and tellurium. EXAMPLE - The powders of copper (Cu), indium (In), gallium (Ga) and selenium (Se) were mixed, and the mixture was melted and fully alloyed in a pressurized enclosed vessel at 1000 degrees C. The resulting bulk material was then used to produce a target suitable for use in a direct current sputtering system. This target and a pure Se target was then used in a magnetron co-sputtering system to deposit a thin copper indium gallium selenium (CIGS) film with a chemical composition of Cu(0.9)In(0.7)Ga(0.3)Se(1.6) on a substrate (soda lime glass coated with a 0.7 m2 thick molybdenum layer). The film was heated in the presence of hydrogen selinide for 10-30 minutes at a 400-500 degrees C. During this process, additional Se was incorporated into the film, thus to obtain the film having a film composition of Cu(0.9)In(0.7)Ga(0.3)Se(2).