Design and Modeling of High-Performance DBR-Based Resonant-Cavity-Enhanced GeSn Photodetector for Fiber-Optic Telecommunication Networks

TLDR: In this article, a distributed Bragg reflector (DBR)-based resonant-cavity-enhanced (RCE) GeSn photodetector on Si substrates was proposed to achieve high-performance photoderetection in terms of responsivity and 3-dB bandwidth for the short-wave infrared (SWIR) high-speed applications.

Abstract: In this work, we present a novel distributed Bragg reflector (DBR)-based resonant-cavity-enhanced (RCE) GeSn photodetector on Si substrates to achieve high-performance photodetection in terms of responsivity and 3-dB bandwidth (BW) for the short-wave infrared (SWIR) high-speed applications. The proposed structure consists of Si/SiO2 distributed Bragg reflectors (DBRs) to enhance the performance of the device. The top and bottom DBRs create a high-quality ( ${Q}$ ) optical cavity to enable multiple pass reflection schemes to increase the responsivity and also high wavelength selectivity with a sharp response. In addition, with an increase in Sn concentration in the active ( i- GeSn) layer, the photodetection range extends to longer wavelengths due to the shrinkage of bandgap energy. The calculated result shows an enhanced 3-dB BW and responsivity as compared to the existing p-i-n PDs. Therefore, the proposed DBR-based RCE GeSn PD can be a promising device for high-speed SWIR photodetection applications.