Inverted planar avalanche photodiode

An apparatus, comprising:

• a semiconductor substrate layer including a first type of semiconductor material;
• a multiplication layer including the first type of semiconductor material disposed proximate to the semiconductor substrate layer;
• an absorption layer including 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, wherein the absorption layer is optically coupled to receive and absorb an optical beam;
• an n+ doped region of the first type of semiconductor material defined at a surface of the multiplication layer opposite the absorption layer, wherein 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;
• first metallic contact coupled to the n+ doped region at the surface of the multiplication layer opposite the absorption layer to apply a bias voltage to the n+ doped region;
• and
• a p+ doped region in the absorption layer, wherein the p+ doped region extends only partially into the absorption layer.