High-Performance Ge PIN Photodiodes on a 200 mm Insulator with a Resonant Cavity Structure and Monolayer Graphene Absorber for SWIR Detection
Jiahan Yu, Xuewei Zhao, Yuanhao Miao, Jiale Su, Zhenzhen Kong, Hongxiao Li, Yuanyuan Wu, Ziwei Zhou, Bo Wang, Tianchun Ye, Henry H. Radamson
Abstract
High-responsivity and low dark current resonant-cavity-enhanced (RCE) Ge PIN photodiodes with a monolayer graphene absorber were demonstrated on a 200 mm insulator. Ge was grown on the donor Si wafer, whereas the acceptor wafer contained a two-period poly-Si/SiO 2 as a distributed Bragg reflector (DBR) mirror. Then, a direct wafer-bonding technique was adopted to transfer the Ge layers on the poly-Si/SiO 2 DBR mirror, thereby forming the RCE Ge PIN photodetectors on the insulator with mesa diameters ranging from 10 to 100 μm. At −1 V reverse bias voltage, average responsivities of 0.67 and 0.85 A/W at 1550 and 1310 nm were achieved due to the combined function of poly-Si/SiO 2 DBR mirror, high-quality Ge active layer, and 2D graphene. The monolayer graphene was transferred from a Cu foil on the chips, which increased the responsivity of the Ge PIN photodetectors at 1310 and 1550 nm by 11.6 and 7.6%, respectively. The dark currents of the detectors at room temperature were in the nanoampere range, for example, the 10 μm detector exhibited a dark current of 5.75 nA. The novelty of our results is based on the integration of a novel DBR mirror below the Ge PIN photodetectors with a graphene absorber on the top. This indicates a significant improvement in the performance of the current Ge PIN photodetectors and a promising technique route to optimize the low-cost and CMOS-compatible short-wave infrared imaging chips in the near future.