The high photoresponsivity of this device is attributed to the high active surface to volume ratio, together with the high carrier transport and collection efficiency through graphene. The inset of
Fig. 4 shows the external quantum efficiency (EQE) of the photo-detector calculated using the equation:EQE=Rxhv/q, where hv is the energy of the incident photon in electronvolts, q is the electron charge and R is the photoresponsivity of the UV photodetector.