Design and Optimization of InAs Waveguide- Integrated Photodetectors on Silicon via Heteroepitaxial Integration for Mid- Infrared Silicon Photonics

Waveguide-integrated photodetectors (PDs) play a crucial role in mid-infrared (MIR) silicon photonics, serving vital functions in sensing and communication applications. III-V semiconductors are widely used in MIR PDs, and many state-of-the-art III-V PDs on Si still require complicated integration methods. Heteroepitaxial growth technology is a competitive approach for large-scale integration; however, buffers capable of simultaneously achieving heteroepitaxial growth and optical coupling are limited in the MIR region. In this paper, we report a waveguide-integrated InAs PD on Si, incorporating a GaAs/Ge buffer design based on interfacial misfit (IMF) technology. We optimize the geometric structure and calculate the optoelectronic properties at a wavelength of 3 μm. For our simulated parameters, the optimal PD achieves a responsivity of 2.77 A/W and a detectivity of 4.68×10⁹ cm·Hz^1/2·W^-1 at -1V. This work suggests a promising avenue to further develop high-detectivity and high-speed PDs for MIR silicon photonics.