![]() This coupling, in turn, causes the channel gate voltage to change, and this structure can produce extreme modifications in the graphene’s electrical signal and carrier density. In a photogating device, photosensitizers are situated close to a graphene channel, such that they undergo coupling with incident light. The use of photogates may be the most viable solution, because this technique provides the greatest increase in responsivity while also improving quantum efficiency. Work to date aimed at increasing graphene responsivity has identified the use of dissimilar electrodes, 5, 7 pn-junctions, 8, 9 bolometers, 10 thermopiles, 11 optical cavities, 12, 13 plasmonic resonance devices, 14- 16 dual graphene sheets with tunneling morphologies, 17 nanoribbons 18 and photogates 19- 28 as possible approaches to this goal. One challenge is the minimal optical absorbance of graphene (2.3% 3) which limits practical applications. 2 Consequently, this material could be used to produce low-cost 2 broadband photodetectors 3 with increased responsiveness, 4- 6 capable of functioning from the terahertz to ultraviolet frequencies. 1 Graphene can also be synthesized much less inexpensively than typical multicomponent semiconductors, using chemical vapor deposition (CVD). Graphene is made of two-dimensional, atomically-thin layers of carbon atoms and exhibits unique optoelectrical properties, including an exceptional broadband photoresponse and significant carrier mobility. The results of this study are expected to contribute to the realization of low-cost, mass-producible, high-responsivity, graphene-based infrared sensors. 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 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. Unwanted carrier scattering that can be caused by the substrate is also suppressed by the lower graphene layers when turbostratic stacked graphene is applied. Furthermore, it is relatively easy to fabricate CVD graphene layers having sizes suitable for the mass production of electronic devices. The turbostratic stacking can be accomplished simply by the repeated transfer of graphene monolayers produced by CVD. ![]() ![]() This form of graphene also exhibits higher carrier mobility and greater conductivity than monolayer CVD graphene. 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. The responsivity of such devices correlates with the carrier mobility of the graphene, and so improved mobility is critical. This effect was induced by situating photosensitizers around a graphene channel such that these materials coupled with incident light and generated large electrical changes. 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.
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