| abstract |
Described is a semiconductor photo detector comprising, between a lower electrode and an upper electrode, an optical absorption layer which generates photo carriers, receiving light and an amplification layer which amplifies the photo carriers so generated. In the semiconductor photo detector, the amplification layer is formed of a well layer which causes an avalanche phenomenon and a barrier layer which has a band gap larger than that of the optical absorption layer. The well layer is formed of a crystal substance, by which at the interface with the barrier layer, the energy value of the conduction band of the photo carriers in the well layer is lower than that in the barrier layer and at the same time, the difference in the energy value of the conduction band between the well layer and the barrier layer is larger than the band gap between the valence band and the conduction band of the well layer. |