InGaAs/Si PIN photodetector with low interfacial recombination rates realized by wafer bonding with a polycrystalline Si interlayer
Jinlong Jiao, Ruoyun Ji, Liqiang Yao, Yingjie Rao, Shaoying Ke, Jianfang Xu, Yibo Zeng, Cheng Li, Guangyang Lin, Wei Huang, Songyan Chen
Abstract
In this Letter, we proposed a robust InGaAs/Si bonded heterojunction by polycrystalline Si (poly-Si) and amorphous interlayers. The ultra-thin amorphous layer is induced through Ar plasma treatment. The synergism of poly-Si and amorphous interlayers effectively blocks the lattice mismatch and releases the interfacial thermal stress. A bubble- and defect-free bonding interface is achieved even if after annealing at 500 °C, demonstrating compatibility with high-temperature processes. The heavily doped poly-Si interlayer sweeps the electric field from the poly-Si layer and concentrates in the amorphous layer, rendering electron tunneling through the bonding interface and reducing the interfacial recombination rates. As a result, the bonded InGaAs/Si PIN photodetector harvests a saturated and low dark density of 0.26 mA/cm2 at −1 V and a high rectification ratio of 3.5 × 105 at ±1 V. Additionally, the non-optimized device achieves a high responsivity of 0.82 A/W at 1550 nm. These results indicate that the proposed bonding strategy provides a viable route to tackle the electronic, optical, and thermal barriers of integrating single-crystal InGaAs into Si platforms. This enables the photodetection of InGaAs/Si devices with a high signal-to-noise ratio.