Patent ID: 8008688
Filing Date: 2011-08-30
Classification: H01L,Y02E

Abstract:
1. A photodiode comprising: a substrate of semiconductor material; a layer stack, disposed on a top surface of the substrate, wherein the layer stack includes a first buffer layer of extrinsic semiconductor material of a first conductivity type, for accommodating lattice mismatch; an absorption layer of intrinsic semiconductor material, for absorbing light to generate current carriers, disposed on a top surface of the layer stack; a grading layer of intrinsic semiconductor material, for facilitating current flow, disposed on a top surface of the absorption layer; a blocking layer of extrinsic semiconductor material of the first conductivity type, for inhibiting current flow, disposed on a top surface of the grading layer with exception of a window region of the top surface of the grading layer, wherein the window region of the top surface of the grading layer is smaller in area than the top surface of the grading layer; and a window mesa of extrinsic semiconductor material of a second conductivity type, for transmitting light to the absorption layer, disposed only on a window region of a top surface of the blocking layer and on the window region of the top surface of the grading layer, wherein the window region of the top surface of the blocking layer is smaller in area than the top surface of the blocking layer.