Fig. 1. Preparation processing of laser induced nitrogen-doped graphene

Fig. 2. SEM images of (a) LIG and (b)-(d) N-LIG with doping con-centration of 1 wt%, 3 wt% and 5 wt% respectively

Fig. 3. (a), (b) The element mapping of LIG and N-LIG; (c), (d) EDS and element ratio of LIG and N-LIG

Fig. 4. (a) Raman spectra of PI, LIG and N-LIG; (b) \begin{document}${I}_{\rm D}/{I}_{\rm G}$\end{document} and \begin{document}${I}_{2 \rm D}/{I}_{\rm G}$\end{document} of LIG and N-LIG as a function of doping content

Fig. 5. (a) XPS full spectrum of LIG and N-LIG; (b) Percentage distribution of C, N, and O elements for LIG and N-LIG

Fig. 6. (a), (b) C1s spectral peak fitting results of LIG and N-LIG; (c), (d) N1s spectral peak fitting results of LIG and N-LIG

Fig. 7. (a) The resistance of LIG and N-LIG with different doping content; (b) Dark currents of LIG and N-LIG with different doping content at bias voltages from −5.0 to 5.0 V

Fig. 8. Photocurrent curves of LIG and N-LIG with different doping content under irradiated by a 630 nm light source

Fig. 9. Photocurrent curves of a N-LIG photodetector at illumination wavelength of 343, 630 and 1 550 nm

Fig. 10. The responsivity of N-LIG photodetector at illumination wavelength of 343, 630 and 1 550 nm