Solid state imaging device and fabrication method for the same

A solid state imaging device comprising:

• a circuit unit formed on a substrate;
• and
• a photoelectric conversion unit including a lower electrode layer placed on the circuit unit, a compound semiconductor thin film of chalcopyrite structure which is placed on the lower electrode layer and functions as an optical absorption layer, and an optical transparent electrode layer placed on the compound semiconductor thin film,
• wherein the lower electrode layer, the compound semiconductor thin film, and the optical transparent electrode layer are laminated one after another on the circuit unit, and
• wherein the compound semiconductor thin film includes a first region and a second region sequentially in a direction from the optical transparent electrode layer toward the substrate, atomic concentration of Ga in the first region is higher than atomic concentration of In in the first region, and atomic concentration of Ga in the second region is lower than atomic concentration of In in the second region.