TY - JOUR
T1 - F4-TCNQ on Epitaxial Bi-Layer Graphene
T2 - Concentration- and Orientation-Dependent Charge Transfer at the Interface
AU - Chattopadhyay, Sudeshna
AU - Munya, Vikas
AU - Kumar, Ravinder
AU - Pal, Dipayan
AU - Bandyopadhyay, Sucheta
AU - Ghosh, Arpan
AU - Yogi, Priyanka
AU - Koch, Julian
AU - Pfnür, Herbert
N1 - Funding Information:
We acknowledge support from the Deutsche Akademischer Austauschdienst (DAAD) who funded the project under the “A New Passage to India” program between Leibniz Universität Hannover and Indian Institute of Technology Indore. We would also like to acknowledge Project No. SR/FST/PSI/225/2016 under the FIST program of the DST, Government of India, for Raman characterization facility. This work is partially supported by the Science and Engineering Research Board (SERB), India Project No: CRG/2020/005595. V.M. is thankful to CSIR-UGC, New Delhi, under the UGC-Ref. No.: 1364/(CSIR-UGC NET JUNE 2018), and R.K. is thankful to DST-INDIA, New Delhi, under the Award No. IF190536 for providing the fellowships.
PY - 2022/12/27
Y1 - 2022/12/27
N2 - Bi-layer epitaxial graphene (BLG) on 6H-SiC(0001) (EG/SiC) was grown and modified by thermal deposition of the molecular electron acceptor tetrafluoro-tetra cyano quinodimethane (F4-TCNQ). The surface-modified system, F4-TCNQ/EG/SiC, was studied by X-ray photoelectron spectroscopy (XPS) and angle-resolved polarized Raman spectroscopy (ARPRS). XPS results indicate that bonding of deposited F4-TCNQ molecules depends on their concentration. Although bonding through the cyano groups is present at all concentrations, charge transfer from graphene to fluorine is evident only at sub-monolayer concentrations. The corresponding change in bond character is coupled with a change in molecular orientation. Raman spectroscopy not only provides results consistent with the findings from the XPS study but also reveals a significant degree of molecular stacking above the monolayer concentration. Thus, both the variation of the acceptor concentration and the number of graphene layers provide further handles to manipulate charge and doping that may be useful in device applications.
AB - Bi-layer epitaxial graphene (BLG) on 6H-SiC(0001) (EG/SiC) was grown and modified by thermal deposition of the molecular electron acceptor tetrafluoro-tetra cyano quinodimethane (F4-TCNQ). The surface-modified system, F4-TCNQ/EG/SiC, was studied by X-ray photoelectron spectroscopy (XPS) and angle-resolved polarized Raman spectroscopy (ARPRS). XPS results indicate that bonding of deposited F4-TCNQ molecules depends on their concentration. Although bonding through the cyano groups is present at all concentrations, charge transfer from graphene to fluorine is evident only at sub-monolayer concentrations. The corresponding change in bond character is coupled with a change in molecular orientation. Raman spectroscopy not only provides results consistent with the findings from the XPS study but also reveals a significant degree of molecular stacking above the monolayer concentration. Thus, both the variation of the acceptor concentration and the number of graphene layers provide further handles to manipulate charge and doping that may be useful in device applications.
UR - https://www.scopus.com/pages/publications/85143986089
U2 - 10.1021/acs.langmuir.2c02676
DO - 10.1021/acs.langmuir.2c02676
M3 - Article
C2 - 36512752
AN - SCOPUS:85143986089
SN - 0743-7463
VL - 38
SP - 16067
EP - 16072
JO - LANGMUIR
JF - LANGMUIR
IS - 51
ER -