High-performance, broadband Si photodiode by integrating graphene

Photodiodes are essential for effective photodetection in optoelectronic applications, and enhancing their performance has been a key focus of ongoing research. Here, we demonstrate a planar silicon photodiode integrated with graphene, which enables amplification in both responsivity and detectivity compared to reference photodiodes, with improvements by several orders of magnitude. This amplification leads to a distinct behavior: unlike conventional photodiodes, where responsivity typically decreases at shorter wavelengths beyond the peak detection, this device maintains a nearly constant responsivity over a wide spectral range—from its peak detection at 900 nm down to 600 nm. Notably, at shorter wavelengths, its responsivity even surpasses that of commercial silicon photodiodes. These behaviors are analyzed through the redistribution of photoexcited carriers in the hybrid structure, which enhances the external quantum efficiency, yielding results consistent with our observations. These findings highlight a promising approach for advancing highly sensitive and broadband photodetection technology for various applications.