Planar InP-InGaAs avalanche photodetectors with n-multiplication layer exhibiting a very high gain-bandwidth product

A planar separate absorption, grading, charge, and multiplication (SAGCM) avalanche photodiode (APD) structure was designed and fabricated, allowing for an updoped multiplication layer without the use of guard rings. A very high gain-bandwidth (GBW) product of 93 GHz and DC gains exceeding 1000 have been measured for a 30- mu m-diameter device. This GBW is, to the author's knowledge, the highest reported to date in any III-V APD. In principle, the useful gain-bandwidth product of SAGCM structures is not limited by the tunneling limit in the InP avalanche region of 140 GHz for conventional separate absorption, grading, and multiplication (SAGM) structures.<
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