High-speed resonant-cavity avalanche photodiodes with separate absorption and multiplication regions

The performance of conventional photodiodes is limited by an intrinsic tradeoff between quantum efficiency and bandwidth. We have successfully demonstrated that resonant-cavity photodiodes can simultaneously achieve high quantum efficiency and wide bandwidth, The resonant-cavity approach lengthens the effective absorption thickness through multiple reflections between two parallel mirrors. Previously, it has been shown that resonant-cavity, separate-absorption-and-multiplication (SAM) avalanche photodiodes (APDs) exhibit high peak external quantum efficiency (similar to 75%), low dark current and low bias voltage (<15V). In this paper, we describe the frequency response of resonant-cavity AlGaAs/GaAs/InGaAs SAM APDs. A unity-gain bandwidth of 23 GHz and a high gain-bandwidth product of 130 GHz have been achieved Also, low multiplication noise characteristics ( 0.2<k<0.3) are reported.