An avalanche photodetector is disclosed. An apparatus according to aspects of the present invention includes a semiconductor substrate layer including a first type of semiconductor material. The apparatus also includes a multiplication layer including the first type of semiconductor material disposed proximate to the semiconductor substrate layer. The apparatus also includes an absorption layer having a second type of semiconductor material disposed proximate to the multiplication layer such that the multiplication layer is disposed between the absorption layer and the semiconductor substrate layer. The absorption layer is optically coupled to receive and absorb an optical beam. The apparatus also includes an n+ doped region of the first type of semiconductor material defined at a surface of the multiplication layer opposite the absorption layer. A high electric field is generated in the multiplication layer to multiply charge carriers photo-generated in response to the absorption of the optical beam received in the absorption layer.