Fig. 6. (a) Capacitance–voltage–frequency (C–V–f) measurement setup to study the graphene–WS2 and WS2–graphene interface characteristics. The inkjet-printed graphene–WS2–graphene heterostructure device enacts the behavior of two Schottky diodes in series with each other. The graphene–WS2 junction showed a non-ohmic rectifying behavior suggestive of its Schottky diode type behavior. (b) Capacitance at various frequencies as a function of bias voltage. The C–V measurements exploit the formation of the depletion region and charging and discharging of capacitance formed within the junction. (c) Capacitance–frequency measurement demonstrating the strong dependence of capacitance with frequency. The decrease in capacitance with frequency is accredited to reduction or annihilation of interface trapped states.
