1. A solid-state imaging device, comprising: a light-receiving portion, where a photoelectric conversion is carried out, formed in a semiconductor substrate; an optical filter layer formed above the surface of the semiconductor substrate in which the light-receiving portion is formed; and quantum dots having substantially equal diameters formed in the optical filter layer, wherein the quantum dots have higher refractive indexes than the refractive index of the optical filter layer in which the quantum dots are embedded, and further wherein the quantum dots are formed from Si material that is applied over the light-receiving portion during formation of the optical filter layer, and wherein the optical filter layer in which the quantum dots are embedded is made of silicon nitride.