InAlAs/InGaAs avalanche photodiode with an optimized multiplication layer

In this paper, the trade-off between gain-bandwidth product (GBP) and dark current of an InAlAs/InGaAs avalanche photodiode (APD) was studied by optimizing multiplication layer. An optimized multiplication layer with 200 nm was proposed to improve the GBP and reduce the dark current. The fabricated InAlAs/InGaAs APD shows an excellent performance which is consistent with the calculated results. A high responsivity of 0. 85 A/W (M=1) at 1. 55 mu m and a high GBP of 155 GHz was achieved, whereas the dark current is as low as 19 nA at 0. 9 V-b. This study is significant to the future high-speed transmission application of the avalanche photodiodes.