High-gain bandwidth product of wafer-bonded near-infrared III-V/silicon APD using polycrystalline silicon bonding layer

Abstract

Avalanche photodiode (APD) is a highly sensitive photodetector commonly used in applications, such as optical fiber communication and LIDAR. However, the 7.7% lattice mismatch between InGaAs and Si creates challenges in growing high-quality InGaAs thin films on Si substrates. Heterogeneous bonded techniques or semiconductor intermediate bonded techniques can effectively resolve this issue, while it is difficult to achieve an ultra-high gain bandwidth product of the APDs. This work designs the wafer-bonded InGaAs/Si APDs with a Poly-Si bonding layer as the charge layer, which is different from the conventional separation absorption gradient multiplication (SAGCM) APD. The doping concentration of the polysilicon (Poly-Si) bonding layer on the performance of the InGaAs/Si APD is calculated. The maximum value of the gain bandwidth product of the APD reaches 350 GHz when the doping concentration of the Poly-Si is set to be 2 × 1017 cm−3. This work may provide guidance for the fabrication of the InGaAs/Si APDs with ultra-high gain bandwidth product.