Upon increasing the excitation power (Figure , sub-WS2 bandgap excitation), the obtained photocurrent demonstrates a unique superlinear dependence with a fitted power law of P ~ 1.38 (black dots and red line). This is in contrast to the conventional saturated absorption with sub-linear power dependence (Supporting Information Section 1), and we interpret this finding with thermal activation of carriers over the Schottky barrier between WS2 and graphene . In addition, the device exhibits a high responsivity of approximately 9 A/W at 779 nm and 22.6 mW/cm 2 excitation power density (blue squares).