"When using TiN as a middle layer 36 b of the first electrode, it is preferable to irradiate ultraviolet light to large the work function of TiN. For the layer 36 c of the first electrode, a metal material reflective of light, typically, a metal material mainly containing Al or Ag, is preferred, and the thickness of the layer is set to 100 to 600 nm." . . . . . . .