
Intra-/Inter-Chip Optical Communications 289
FIGURE 7.29
Scheme of the germanium wavelength-integrated avalanche photodetector
(APD) described in reference [7].
crystal Ge waveguide. This formation is made also before the activation of
the source/drain implants in the CMOS process. This technique overcomes
two important challenges. The first one is the lattice mismatches, already
commented on, produced for a direct growth of Ge on S. The second one is
the temperature problems derived from the fact that while the CMOS process
reaches temperatures over 1000
◦
C before metal contacts are created and these
cannot be over 550
◦
C after their formation, Ge gro