Enhanced photogating effect with turbostratic stacked graphene photodetectors for developing high-responsivity infrared sensors

This study investigated the fabrication and performance of highly responsive photodetectors, constructed of turbostratic stacked graphene produced via chemical vapor deposition (CVD) and using the photogating effect. This effect was induced by situating photosensitizers around a graphene channel such that these materials coupled with incident light and generated large electrical changes. The responsivity of such devices correlates with the carrier mobility of the graphene, and so improved mobility is critical. This work assessed the feasibility of using turbostratic stacked CVD graphene to improve mobility since, theoretically, multilayers of this material may exhibit linear band dispersion, similar to monolayer graphene. This form of graphene also exhibits higher carrier mobility and greater conductivity than monolayer CVD graphene. The turbostratic stacking can be accomplished simply by the repeated transfer of graphene monolayers produced by CVD. Furthermore, it is relatively easy to fabricate CVD graphene layers having sizes suitable for the mass production of electronic devices. Unwanted carrier scattering that can be caused by the substrate is also suppressed by the lower graphene layers when turbostratic stacked graphene is applied. The infrared response properties of the multilayer devices fabricated in the present work were found to be approximately tripled compared with those of a monolayer graphene photodetector. It is evident that turbostratic stacked CVD graphene, which can be produced on a large scale, serves to increase the responsivity of photodetectors in which it is included. The results of this study are expected to contribute to the realization of low-cost, mass-producible, high-responsivity, graphene-based infrared sensors.