Patent ID: 8829566

Claim:
An apparatus, comprising: a first region including a first intrinsic material layer different from and directly in contact with a second intrinsic material layer such that light incident on a first side of the first intrinsic material layer passes through the first side to a second side of the first intrinsic material layer opposite the fist side and enters the second intrinsic material layer, the first intrinsic material layer to absorb light in a first range of wavelengths and the second intrinsic material layer to absorb light in a second range of wavelengths, wherein the second intrinsic material layer only includes Germanium; a second region proximate to and distinct from the first region, the second region including another intrinsic semiconductor material layer; a first doped layer disposed between the first region and the second region; a second doped layer disposed adjacent to the second region on an opposite side as the first doped layer; a contact layer disposed within the first intrinsic material layer; and doped guard rings disposed within the first intrinsic material layer and at least partially surrounding the contact layer to confine an electric field, wherein the light enters the first region incident through the contact layer between the doped guard rings, wherein photo-generated charge carriers that are generated in the first region and swept into the second region are multiplied in the second region when a voltage is applied across the contact layer and the second doped layer.