Semiconductor stacked body and light-receiving device

A semiconductor stacked body, comprising:

• a base layer containing a III-V group compound semiconductor and having n-type conductivity;
• a light-receiving layer containing a III-V group compound semiconductor;
• a control layer containing a III-V group compound semiconductor and disposed in contact with the light-receiving layer;
• a diffusion blocking layer containing a III-V group compound semiconductor and a p-type impurity that generates a p-type carrier, the diffusion blocking layer having a p-type impurity concentration of 1×1016 cm−3 or less;
• and
• a contact layer containing a III-V group compound semiconductor and having p-type conductivity,
• the base layer, the light-receiving layer, the control layer, the diffusion blocking layer, and the contact layer being stacked in this order,
• wherein a concentration of an element in the control layer, the element being identical to a group V element contained in the light-receiving layer, is lower on a main surface of the control layer adjacent to the diffusion blocking layer than on a main surface of the control layer adjacent to the light-receiving layer.