Performance Enhancement of Graphene Photodetectors via In Situ Preparation of TiO₂ on Graphene Channels

Abstract Graphene has been considered a promising material for high‐performance photodetectors due to its broad light‐absorption bandwidth and fast photoresponse time. However, weak light absorption (2.3%) in monolayer graphene results in the relatively low photoresponsivity of graphene photodetectors (GPDs). Moreover, the operation stability of GPDs has become another commercialization bottleneck due to the environmental sensitivity of graphene materials. Hence, developing a compact GPD with high photoresponsivity and high stability is critical and significant. Here, an in situ, thermally oxidized TiO₂ layer is used to enhance both the photoresponsivity and stability of a metal–graphene–metal photodetector. Moreover, the fabricated GPDs operate well under zero bias, avoiding the large dark current produced in traditional GPDs. These results address key challenges for high‐performance photodetectors and are promising for the development of complementary metal–oxide–semiconductor compatible graphene‐based optoelectronic applications, such as monolithic optoelectronic‐integrated broadband image sensor chips.