Figure 1.

(a) Schematic view of the device and (b) equivalent circuit; (c) I-V characteristic of the Gr/Si junction for decreasing temperature from $400\mathrm{K}$ to $300\mathrm{K}$. The temperature values listed in the figure are measured with an error of $\pm 1\mathrm{K}$. The inset shows the I-V characteristic at $310\mathrm{K}$ in linear scale; (d) Richardson plot of $\ln \left({\mathrm{I}}_0/{\mathrm{T}}^2\right)$ versus ${10}^3/\mathrm{T}$.