The effect of doping Graphene Quantum Dots with K, B, N, and Cl on its emitted spectrum

In this work, the effect of doping Graphene Quantum Dots (GQDs) on their emission spectra has been studied. First, graphene has been deposited on SiC substrate by using sublimation method. Second, doped-GQDs have been distributed on the surface of graphene via drop casting. The structure of the samples have been studied and characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), and Micro-RAMAN spectrometer. Emitted spectra of the doped samples have been studied, and the results show the highest intensity is for K doped samples. The XRD pattern of epitaxial graphene on SiC, represents the structures of graphene and SiC. AFM image shows homogenous surface of epitaxial graphene grown on SiC. Reflectance mapping images obtained from Micro-RAMAN spectrometer confirms the existence of mono- and bi-layers of graphene. The SEM and AFM results show homogenous dispersion of GQDs on the substrate. Results of the emitted spectra of the samples show that by increasing doping of GQDs with B from 0.75% to 1.5% and with K from 2% to 4%, the intensities of emission spectra from GQDs have been increased. Moreover, by increasing doping with N and Cl from 2% to 4%, these emission spectra from GQDs have been decreased. Also, the peaks intensity of K doped GQDs (K-GQDs) are higher than those of B, and for N-GQDs are more than those of Cl. In general, the highest and the lowest peak is for K and Cl, respectively.