an avalanche photodetector is disclosed . an apparatus according to aspects of the present invention includes a mesa structure defined in a first type of semiconductor . the first type of semiconductor material includes an absorption region optically coupled to receive and absorb an optical beam . the apparatus also includes a planar region proximate to and separate from the mesa structure and defined in a second type of semiconductor material . the planar region includes a multiplication region including a p doped region adjoining an n doped region to create a high electric field in the multiplication region . the high electric field is to multiply charge carriers photo - generated in response to the absorption of the optical beam received in the mesa structure .