240-GHz Gain-Bandwidth Product Back-Side Illuminated AlInAs Avalanche Photodiodes

We demonstrate an AlInAs-InGaAs separate absorption, grading, and multiplication avalanche photodiode (APD) with a very thin avalanche layer operating at 1550 nm for 10-Gb/s optical transmission achieving simultaneously high responsivity (0.9 A/W at M = 1), very low excess noise factor ( F ( M =10) = 3), and very high gain-bandwidth product of 240 GHz. To our knowledge, this is the first time that a back-side illuminated planar junction AlInAs-InGaAs APD achieved such performances.