TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The oxide film having the insulating properties is the porous anodized film. The light-absorbing layer contains a compound comprising cadmium sulfide/cadmium telluride, copper-indium-selenium (CIS) and copper-indium-gallium-selenium (CIGS). EXAMPLE - The aluminum rolled plate (comprising (in wt.%): silicon (0.003); iron (0.003); manganese (4); zinc (0.001); titanium (0.001); lead (0.0001); nickel (0.0001); boron (0.0001); and sodium (0.0010)) was degreased by immersion in an acidic electrolytic solution containing sulfuric acid (170 g/l) at 60 degrees C for 30 seconds, then rinsed with water, and the water was further removed with nip rollers. An anodized layer (insulating layer) was formed in electrolytic cells. The thickness of the anodized film was adjusted with the electrolysis time. Then, rinsing with water and removal of the water with nip rollers were carried out. Anodizing treatment was carried out using an aqueous solution containing 170 g/l of sulfuric acid (14 ml) (and also containing g/l of aluminum ions adjusted by the addition of aluminum sulfate) at a current density of 25 A/dm2 and a solution temperature of 40 degrees C. A direct current was used and the aluminum plate served as the anode. An aqueous solution obtained by adding 0.05 mol/l of sodium tetraborate to an aqueous solution containing 0.5 mol/L of an aqueous boric acid solution, was used for sealing. Sealing was carried out at a solution temperature of 20 degrees C. A direct current was used and the aluminum plate and the carbon electrode served as the anode and the counter electrode, respectively, and the distance between the aluminum plate and the counter electrode was 2 cm. A direct current power supply with a constant voltage was used and the voltage between the aluminum plate and the counter electrode was set to 400V. The current flowed at a current density of 0.5 A/dm2 for 1 minute from the beginning and gradually decreased to approach 0 A/dm2 5 minutes later. The total electrolysis time was 5 minutes. Then, the plate was rinsed with water and dried after removal of the water with nip rollers to give the substrate.