TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Method: The step of forming the film comprises depositing a copper (Cu) layer over the base; and depositing two additional layers including gallium (Ga) and indium (In) over the Cu layer, where the Ga/(Ga+In) ratio is 0-0.7. The steps of depositing the Cu layer and depositing the two additional layers are carried out by electroplating. The step of forming the separator layer comprises electroplating. The step of forming the source layer comprises vapor deposition. The step of forming the cap layer comprises vapor deposition. Preferred Condition: The step of reacting includes rapidly heating the film, the separator layer, the source layer and the cap layer to the reaction temperature with a heating rate of greater than or equal to 50 degrees C per seconds. Preferred Dimension: The thickness of the film is 500-1000 nm, the thickness of the separator layer is 100-1000 nm, the thickness of the source layer is 20-100 nm and the thickness of the cap layer is 800-3000 nm. The thickness of the dopant film is 5-20 nm. Preferred Component: The film further includes Ga. It further includes a fourth additive material, where a ratio of the molar amount of In to the total molar amounts of In, Ga, Cu, and the fourth additive material is 0.25-0.6. The fourth additive material includes dopant material(s) from sodium (Na), potassium (K) or lithium (Li). The molar ratio of Cu/In+Ga in the film is 0.8-1.0. The separator layer further includes a first additive material, where a ratio of the molar amount of the Group VIA material to the total molar amounts of the Group VIA material and the first additive material is 0.95-1.0. The Group VIA material includes selenium or tellurium, and the first additive material includes Cu, In, or Ga and a dopant material from Na, K or Li. The source layer further includes a second additive material, where a ratio of the molar amount of Ga to the total molar amounts of Ga and the second additive material is 0.7-1.0. The second additive material includes Cu, In, and a dopant material from Na, K or Li. The cap layer further includes a third additive material, where a ratio of the molar amount of selenium (Se) to the total molar amounts of Se and the third additive material is 0.95-1.0. The third additive material includes tellurium and a dopant material from Na, K and Li.