Avalanche multiplication photodiode having a buried structure

摘要

A buried structure avalanche multiplication photodiode (APD) is provided with a surface level difference between the multiplication region and guard ring region. The APD has a so-called separated absorption and multiplication region structure comprising an n-InGaAs light absorbing layer and an n-InP multiplication layer. The surface level difference is provided by selective growth of the layer in which the guard ring is formed or selective removal of the layer over the multiplication region. In the APD, the pn junction is level throughout the multiplication region and guard ring region or is made farther apart from the light absorbing layer in the guard ring region than in the multiplication region, and a significant reduction of dark current due to tunneling current in the InGaAs layer and/or InGaAsP layer is obtained. Moreover, the breakdown voltage difference of the pn junction in the multiplication region and the guard ring region has also been increased.