Germanium/silicon avalanche photodetector with separate absorption and multiplication regions

Abstract

A semiconductor waveguide based optical receiver is disclosed. An apparatus according to aspects of the present invention includes an absorption region including a first type of semiconductor region proximate to a second type of semiconductor region. The first type of semiconductor is to absorb light in a first range of wavelengths and the second type of semiconductor to absorb light in a second range of wavelengths. A multiplication region is defined proximate to and separate from the absorption region. The multiplication region includes an intrinsic semiconductor region in which there is an electric field to multiply the electrons created in the absorption region.

What is claimed is: 
     
         1 . An apparatus, comprising:
 an absorption region including a germanium layer and a different, second type of semiconductor layer disposed above the germanium layer, wherein the germanium layer is to absorb light in a first range of wavelengths and the different, second type of semiconductor layer is to absorb light in a second range of wavelengths, wherein the first range of wavelengths includes wavelengths longer than any wavelength of the second range of wavelengths; and   a multiplication region disposed below the absorption region, the multiplication region including an intrinsic semiconductor material to multiply electrons from the absorption region in response to an electric field.   
     
     
         2 . The apparatus of  claim 1 , further comprising a buried oxide layer below the multiplication region. 
     
     
         3 . The apparatus of  claim 2 , wherein the buried oxide layer comprises a buried oxide layer of a silicon-on-insulator (SOI) wafer. 
     
     
         4 . The apparatus of  claim 1 , wherein the multiplication region is adjacent to and disposed between a layer of p−doped silicon and a layer of n+doped silicon. 
     
     
         5 . The apparatus of  claim 1 , wherein the different, second type of semiconductor layer includes a silicon based layer. 
     
     
         6 . The apparatus of  claim 1  further comprising a doped contact layer disposed proximate to the absorption region. 
     
     
         7 . The apparatus of  claim 6  further comprising guard rings defined in the absorption region proximate to the doped contact layer. 
     
     
         8 . The apparatus of  claim 1  wherein the different, second type of semiconductor layer comprises silicon. 
     
     
         9 . The apparatus of  claim 1  wherein the apparatus is a photodetector, wherein the photodetector is one of a plurality of photodetectors arranged in an array to collectively detect an image focused on the array. 
     
     
         10 . The apparatus of  claim 1  further comprising a reflective layer disposed proximate to the multiplication region, wherein the multiplication region is disposed between the absorption region and the reflective layer such that a resonant cavity including the absorption region and the multiplication region is defined between the reflective layer and a surface of the apparatus onto which light is incident. 
     
     
         11 . A system, comprising:
 a photodetector array including a plurality of photodetectors each comprising:   an absorption region including a germanium layer and a different, second type of semiconductor layer disposed above the germanium layer, wherein the germanium layer is to absorb light in a first range of wavelengths and the different, second type of semiconductor layer is to absorb light in a second range of wavelengths, wherein the first range of wavelengths includes wavelengths longer than any wavelength of the second range of wavelengths; and   a multiplication region disposed below the absorption region, the multiplication region including an intrinsic semiconductor material to multiply electrons from the absorption region in response to an electric field; and   an optical focusing element to focus an optical image onto the photodetector array.   
     
     
         12 . The system of  claim 11 , the plurality of photodetectors each further comprising a buried oxide layer below the multiplication region. 
     
     
         13 . The system of  claim 12 , wherein the buried oxide layer comprises a buried oxide layer of a silicon-on-insulator (SOI) wafer. 
     
     
         14 . The system of  claim 11 , wherein the multiplication region is adjacent to and disposed between a layer of p−doped silicon and a layer of n+doped silicon. 
     
     
         15 . The system of  claim 11 , wherein the different, second type of semiconductor layer includes a silicon based layer. 
     
     
         16 . The system of  claim 11  the plurality of photodetectors each further comprising a doped contact layer disposed proximate to the absorption region. 
     
     
         17 . The system of  claim 16 , the plurality of photodetectors each further comprising guard rings defined in the absorption region proximate to the doped contact layer. 
     
     
         18 . The system of  claim 11  wherein the different, second type of semiconductor layer comprises silicon. 
     
     
         19 . The apparatus of  claim 11 , the plurality of photodetectors each further comprising a reflective layer disposed proximate to the multiplication region, wherein the multiplication region is disposed between the absorption region and the reflective layer such that a resonant cavity including the absorption region and the multiplication region is defined between the reflective layer and a surface of the apparatus onto which light is incident.