Fall 2013 IAB & Research Review
September 18 - 19
Photo-MOSFET with Single Crystalline Germanium on SOI by Rapid Melt Growth [BPN609]
As CMOS devices shrink in physical size, electrical interconnects between the devices will consume an ever-greater proportion of total chip power. A promising solution is to use silicon photonics for intra- and inter-chip communications. To be cost effective, both the optical transmitter and receiver should be made small, highly efficient, and CMOS compatible. Shrinking the photodiode will increase sensitivity and energy efficiency, but as it gets very small, the capacitance of the wire to the first amplifying stage in the receiver becomes significant. We present a solution which integrates the photodiode and first stage transistor in the form of an integrated germanium gate photoMOSFET. The rapid melt growth technique is used to integrate high quality single crystal germanium onto a silicon waveguide integrated device in a CMOS process. Due to the high quality of the germanium, the responsivity of the photoMOSFETs can be driven to over 10 A/W at 1550nm. Further scaling of these devices is possible only if the reduced absorption from a small size is addressed. Electromagnetic simulations describe a highly efficient metal-optic cavity, supporting efficient absorption in sub-fF scale devices.