III-V Photodetectors For Silicon Photonics

A team of engineers has demonstrated an improved technique for growing high-performance photodetectors made from III-V materials directly on a platform compatible with silicon photonics. The team’s approach puts together several micropatterning and deposition methods to create a monolithic indium-phosphate/silicon-on-insulator (InP/SOI) platform tuned for growing such devices in various dimensions.

The engineers devised a new method to selectively grow the III-V material InP in parallel with the silicon device layer on an SOI wafer. They patterned the 480-nm-thick silicon layer on the SOI wafer into segments and then encapsulated it with a thin oxide layer. A wet-etching process undercut the top oxide layer to create trenches beneath it, removing the silicon in selected areas and leaving a gap between the overlying encapsulating oxide and the insulating oxide layer beneath the silicon.

InP is then epitaxially grown, in a lateral direction, to fill the gap – creating an “InP-on-insulator” structure directly adjacent to the SOI one. InP bars and membranes of various lengths can sit in-plane with the silicon device layer in the resulting monolithic platform. The architecture allows for smooth light coupling with silicon waveguides while still taking advantage of the superior properties of InP (and other III-V materials) for high-speed photodetection.

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