Tin dioxide quantum dots coupled with graphene for high-performance bulk-silicon Schottky photodetector

Commercial photodetectors have been dominated by bulk silicon (B-Si) due to the maturity of Si technology. However, its relatively poor mobility has impeded B-Si from high-performance applications. Herein, we demonstrate that tin dioxide quantum dots (SnO2-QDs) coupled with graphene produce a Schottky junction with B-Si to drastically promote the performance of the SnO2-QDs/graphene/B-Si Schottky photodetector. This hybrid device is sensitive to broadband illumination covering the UV-vis-NIR region and shows high responsivity of 967.6 A W-1 (nearly 4 orders higher than that of commercial B-Si Schottky photodetectors), with corresponding external quantum efficiency of 2.3 x 105% and detectivity of 1.8 x 1013 Jones. In addition, the hybrid device manifests fast rise and decay times of 0.1 and 0.23 ms, respectively. These figures-of-merit are among the best values of the recently reported B-Si Schottky photodetectors. We also established that the superior performances are attributed to the strong light absorption of the hybrid structure and increased built-in potential of the graphene/B-Si Schottky junction, which allows efficient separation of photoexcited electron-hole pairs. These findings pave the way toward the rational design of optoelectronic devices through the synergetic effects of 2D materials with 0D and 3D semiconductors.