Photodiodes with high speed and efficiency are particularly advantageous to the exponential growth of data communication traffic. However, vertical detector design still faces difficulties in improving high responsivity while maintaining low dark current and high bandwidth.

In a recent study published in ACS Applied Electronic Materials, a research team led by Prof. Wang Liang and Prof. Han Zhengfu from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences designed a low-dark-current and high-bandwidth photodiode with improved responsivity.

The researchers achieved epitaxial structure growth with low defect density and high doping accuracy by adjusting the growth parameters such as MOCVD temperature, V/III ratio, and doping concentration.

They designed a plasmonic InP/InGaAs uni-traveling-carrier photodiode with optical antenna arrays, which exhibits a low dark current of 2.52 nA at a −3 V bias voltage, a high bandwidth of over 40 GHz, and a high responsivity of 0.12 A/W. The absorption efficiency of the photodiode shows a 2-fold improvement using plasmonic resonance generated by nanodisks at 1550 nm.

Compared with other devices, its responsivity is enhanced by 147% and its signal-to-noise ratio is higher, which helps provide a high-quality domestic chip for high-speed optical interconnection networks.

This study provides the core chip for optical receiver modules applied to data centers, breaking down barriers in key hardware technology for higher-speed optical modules in the future.