RETRACTED: Morphological and electrical properties of few layer graphene after nitrogen doping by LPCVD technique (Retracted article. See vol. 746, pg. 741, 2018)

Carbon materials doped with only one kind of C-N bonding configuration are a great outlook for studying doping effects on the electronic structure and electrical properties. Synthesis of nitrogen-doped few-layer graphene films on Cu foil is achieved by low pressure chemical vapor deposition (LPCVD). For investigation of nitrogen doped effect on structural, morphological and electrical properties of graphene the reactive gas was a mixture of CH4 and NH3 with the different ratio CH4 and NH3 by volume at the constant pressure of the growth chamber. The N-doped graphene (NG) samples were characterized by Raman spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS). Also in this experiment, the I-V characteristic carried out for study of electrical property of N-doped graphene at different gases mixing ratio with keithley 2361 system. The Raman spectroscopy showed D, G and 2D bound in doped and undoped graphene while we find the intensity of the 2D peak decreases and D peak intensity increases with the increase in the percent of NH3 in gas mixture. Likewise the presence of weak 2D band in all sample suggest that the produced samples are few layer graphene. SEM images showed dendritic-like morphology in undoped graphene and we observed that point like defect created among this morphology by increasing the nitrogen in synthesis process. The XPS results of sample with 25% NH3 in gas mixture confirm the existence of nitrogen in doped graphene which indicates the nitrogen atoms doped in the graphene lattice are mainly in the form of pyridinic nitrogen. The study on electrical properties emphasized that the dependence of current with voltage for all samples was linear like behavior, and sample conductivity was decreased with increasing the percent of nitrogen in gas mixture. The results showed that nitrogen-doped graphene can be successfully synthesized and also chemical nitrogen doping can be change the electrical conductivity of the graphene. (C) 2015 Elsevier B.V. All rights reserved.