▎ 摘　　要

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 similar to 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. (C) 2015 AIP Publishing LLC.