Avalanche photodiode and its manufacturing method.

摘要

The avalanche photodiode comprises a light absorbing semiconductor layer (3); an avalanche gain semiconductor layer (4) having a bandgap greater than that of said light absorbing semiconductor layer; a first p-n junction (5) having a substantially p<+>-n junction and selectively provided in said avalanche gain semiconductor layer (4); a second p-n junction (5 min ) having a substantially graded p-n junction surrounding the periphery of said first p-n junction (5) and a third p-n junction (5 sec ) having a substantially graded p-n junction and surrounding the periphery of said second p-n junction (5 min ). This heterojunction avalanche photodiode is capable of achieving sufficient and uniform avalanche gain in a stepwise p-n junction region corresponding to its light receiving region before a voltage breakdown occurs in its guard ring.