The authors have fabricated and tested heterojunction Ge/Si photodetectors
based on pure Ge epitaxially grown on Si (001) using a two-step UHV-CVD pro
cess followed by cyclic thermal annealing. The detectors exhibit responsivi
ties as high as 550mA/W at 1.32 mu m and 250mA/W at 1.55 mu m and response
limes shorter than 850ps.