Patent ID: 8575650
Filing Date: 2013-11-05
Classification: H01L

Abstract:
1. An avalanche photodiode that forms a stack structure sequentially including an n electrode layer, an n electrode connecting layer, an avalanche multiplication layer, an electric field control layer, a band gap gradient layer, a low-concentration light absorbing layer, a p-type light absorbing layer, and a p electrode layer, wherein the n electrode connecting layer has an n-type region that is disposed to be closer to an inner side than an outer circumference of the avalanche multiplication layer, when viewed from a stack direction, and in the stack structure, a buffer layer comprising InAlAs that has an ionization rate lower than an ionization rate of the avalanche multiplication layer is inserted between the n electrode connecting layer and the avalanche multiplication layer so that there is no contact between the n electrode connecting layer and the avalanche multiplication layer, wherein the buffer layer includes a doping portion comprising InAlAs where impurities are doped at a side of the buffer layer in contact with the avalanche multiplication layer.