Efficient high-speed near-infrared Ge photodetectors integrated on Si substrates

We have fabricated Ge/Si heterojunction photodetectors with high responsivi ties of 550 mA/W at 1.32 mu m and 250 mA/W at 1.55 mu m and time responses shorter than 850 ps. High quality Ge was epitaxially grown on Si using ultr ahigh vacuum/chemical vapor deposition followed by cyclic thermal annealing . The beneficial effect of the post-growth thermal annealing on the electri cal properties of Ge epilayers, due to the reduction of threading-dislocati on densities, is confirmed by the dramatic enhancement of the performance o f the photodetectors. (C) 2000 American Institute of Physics. [S0003-6951(0 0)03410-0].