Figure 4: Carrier transport in the proposed graphene photodetector.
From: Broadband high photoresponse from pure monolayer graphene photodetector
(a) The I–V characteristics of Sample C at 294 K and 12 K, respectively. The fact that the I–V characteristic is linear at 294 K, while becomes nonlinear and maintains highly symmetric indicates that a carrier transport barrier is formed in the GQD array structure, which is caused by the Coulomb blockade of charges. (b) The temperature dependence of the drain current of Sample C is best fitted in a T−1/3 scale. The results show that VRH is the main carrier transport mechanism. The inset shows a good liner fitting of the photocurrent in the logarithmic scale with respect to T−1/3. This suggests that the processed graphene device consists of polydispersed GQDs. (c) The transfer curves of Sample C at different temperatures, in which strong temperature dependence is shown. (d) Differential conductance as a function of VG and VD of Sample C at 12 K and (e) its magnification plot. The diamond-shaped region suggests the Coulomb blockade effect influences the carrier transport.
