A semiconductor photodetector and fabrication process for the same.

摘要

A buried structure avalanche multiplication photodiode (APD) provided with a surface level difference between the multiplication region (AB) and guard ring region (GR). The APD has so-called separated absorption multiplication structure comprising an n-InGaAs light absorbing layer (2) and n-lnP multiplication layer (3). The surface level difference is provided by selective growth of the layer in which guard ring (GR) is formed or selective removing of the layer over the multiplication region (AB). In the APD, the pn junction is leveled throughout the multiplication region (AB) and guard ring region (GR) or is made farther apart from the light absorbing layer (2) in the guard ring region (GR) than in the multiplication region (AB), and a significant reduction of dark current due to tunnelling current in the InGaAs layer (2) and/or InGaAsP layer has been obtained. Moreover, the breakdown voltage difference of the pn junction in the multiplication region (AB) and the guard ring region (GR) has also been increased.