Semiconductor photo-detecting device

A photo-detecting device, comprising:

• a first semiconductor layer;
• a second semiconductor layer located on the first semiconductor layer and comprising a first region and a second region surrounding the first region, wherein the first region comprises a first dopant;
• a light-absorbing layer located between the first semiconductor layer and the second semiconductor layer and comprising a third region and a fourth region surrounding the third region, wherein the third region comprises the first dopant;
• and
• a first interface between the second semiconductor layer and the light-absorbing layer;
• wherein the first dopant of the first region close to the first interface comprises a first doping concentration and the first dopant of the third region close to the first interface comprises a second doping concentration, and the second doping concentration is larger than the first doping concentration.