| 摘要 |
PURPOSE:To increase the photoelectric conversion efficiency by multiplying carriers near a second semiconductor layer in a first semiconductor region. CONSTITUTION:The relation represented by an inequality of Eg2>EVB>=Eg1 where Eg1, Eg2 and EVB respectively represent the energy band gap in a first semiconductor region 1, the energy bad gap in a second semiconductor layer 2 and the barrier due to the band discontinuity in the valance band width of the semiconductor region 1 and the semiconductor layer 2 is to be brought about. When light having a photoenergy higher than Eg2 enters the semiconductor layer 2, electron-hole pairs are made in the semiconductor. The holes out the light-emitted carriers as the minor carriers in the semiconductor layer 2 are shifted in the semiconductor layer 2 passing through the interface with the semiconductor region 1 to be discharged into the region 1 due to the diffusion or the drifting by the electric field in the semiconductor layer 2. Then, the electron-hole pairs are made by the mutual actions of carrier and lattice to release energy making the electron-hole pairs exceeding one pair. Through these procedures, the photoelectric conversion efficiency can be increased. |
