We report on a general method for broadband responsivity enhancement in graphene photodetectors based on the sandwiched graphene structure under total internal reflection. The optical absorption is ∼25% for transverse electric waves for pure monolayer graphene, and the responsivity of pure monolayer graphene photodetectors is 0.012 A/W, which is one or two orders of magnitude larger than the normal incidence excitation. The enhanced responsivity covers a wide wavelength range from 300 to 1550 nm. Further, this method is not limited by the device, and it is a general method used to improve the light-graphene coupling, thus increasing the responsivity of graphene photodetectors largely. And this method allows large area preparation to meet the needs of the free space light detections.
Published in: "Applied Physics Letters".