Germanium advances optical interconnect hope
The new detector is compatible with standard microchip technology because the germanium can be placed selectively in the regions where the photodetectors reside. This compatibility opens the door for making opto-electronic circuits on the same chips as microprocessors and other electronic components.
IBM says that the photodetectors exhibit nearly all of the desirable properties needed for optical interconnects - high bandwidth (speed), high efficiency (40%), low voltage operation (1V), wide spectral window and compatibility with standard microchip fabrication facilities. The GOI technology creates a photodetector that has an optical frequency response of nearly 30GHz, making it, in principle, suitable for detecting signals at speeds over 50Gbits/sec (Gbps).
According to IBM, Ge has outstanding absorption properties at the wavelength typically used for optical transmission over short distances. At this wavelength (850nm), Ge absorbs light about 70 times more efficiently than Si, the semiconductor used to make microprocessors. Since germanium absorbs light so well, the detectors are much smaller and faster than Si photodetectors, and Ge is compatible with the Si fabrication processes.
IBM gave details of the technology at the Device Research Conference on June 22, 2004.
