Germanium photodetector and method of fabricating the same

Abstract

Provided is a germanium photodetector having a germanium epitaxial layer formed without using a buffer layer and a method of fabricating the same. In the method, an amorphous germanium layer is formed on a substrate. The amorphous germanium layer is heated up to a high temperature to form a crystallized germanium layer. A germanium epitaxial layer is formed on the crystallized germanium layer.

1 .- 7 . (canceled) 
     
     
         8 . A germanium photodetector comprising:
 a germanium epitaxial layer disposed directly on a silicon substrate;   a first doped layer on the germanium epitaxial layer; and   a second doped layer disposed under the germanium epitaxial layer, the second doped layer having a different conductivity type from the first doped layer.   
     
     
         9 . The germanium photodetector of  claim 8 , wherein the germanium epitaxial layer has a threading dislocation density of about 2×10 6 /cm 2  or less measured by Secco etching. 
     
     
         10 . The germanium photodetector of  claim 8 , wherein the germanium photodetector has a leakage current of about 100 nA or less at about −1.0 V. 
     
     
         11 . A germanium photodetector comprising:
 a germanium epitaxial layer disposed on a silicon substrate;   a first doped layer on the germanium epitaxial layer; and   a second doped layer disposed under the germanium epitaxial layer, the second doped layer having a different conductivity type from the first doped layer   wherein an interface between the silicon substrate and the germanium epitaxial layer is free from a SiGe buffer.