Probing the charge transfer and electron–hole asymmetry in graphene–graphene quantum dot heterostructure
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In: Nanotechnology, Vol. 33.2022, No. 32, 325704, 20.05.2022.
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T1 - Probing the charge transfer and electron–hole asymmetry in graphene–graphene quantum dot heterostructure
AU - Roy, Rajarshi
AU - Holec, David
AU - Kratzer, Markus
AU - Münzer, Philipp
AU - Kaushik, Preeti
AU - Michal, Lukas
AU - Kumar, Gundam Sandeep
AU - Zajíčková, Lenka
AU - Teichert, Christian
N1 - Publisher Copyright: © 2022 IOP Publishing Ltd.
PY - 2022/5/20
Y1 - 2022/5/20
N2 - In recent years, graphene-based van der Waals (vdW) heterostructures have come into prominence showcasing interesting charge transfer dynamics which is significant for optoelectronic applications. These novel structures are highly tunable depending on several factors such as the combination of the two-dimensional materials, the number of layers and band alignment exhibiting interfacial charge transfer dynamics. Here, we report on a novel graphene based 0D-2D vdW heterostructure between graphene and amine-functionalized graphene quantum dots (GQD) to investigate the interfacial charge transfer and doping possibilities. Using a combination of ab initio simulations and Kelvin probe force microscopy (KPFM) measurements, we confirm that the incorporation of functional GQDs leads to a charge transfer induced p-type doping in graphene. A shift of the Dirac point by 0.05 eV with respect to the Fermi level (E F) in the graphene from the heterostructure was deduced from the calculated density of states. KPFM measurements revealed an increment in the surface potential of the GQD in the 0D-2D heterostructure by 29 mV with respect to graphene. Furthermore, we conducted power dependent Raman spectroscopy for both graphene and the heterostructure samples. An optical doping-induced gating effect resulted in a stiffening of the G band for electrons and holes in both samples (graphene and the heterostructure), suggesting a breakdown of the adiabatic Born-Oppenheimer approximation. Moreover, charge imbalance and renormalization of the electron-hole dispersion under the additional influence of the doped functional GQDs is pointing to an asymmetry in conduction and carrier mobility.
AB - In recent years, graphene-based van der Waals (vdW) heterostructures have come into prominence showcasing interesting charge transfer dynamics which is significant for optoelectronic applications. These novel structures are highly tunable depending on several factors such as the combination of the two-dimensional materials, the number of layers and band alignment exhibiting interfacial charge transfer dynamics. Here, we report on a novel graphene based 0D-2D vdW heterostructure between graphene and amine-functionalized graphene quantum dots (GQD) to investigate the interfacial charge transfer and doping possibilities. Using a combination of ab initio simulations and Kelvin probe force microscopy (KPFM) measurements, we confirm that the incorporation of functional GQDs leads to a charge transfer induced p-type doping in graphene. A shift of the Dirac point by 0.05 eV with respect to the Fermi level (E F) in the graphene from the heterostructure was deduced from the calculated density of states. KPFM measurements revealed an increment in the surface potential of the GQD in the 0D-2D heterostructure by 29 mV with respect to graphene. Furthermore, we conducted power dependent Raman spectroscopy for both graphene and the heterostructure samples. An optical doping-induced gating effect resulted in a stiffening of the G band for electrons and holes in both samples (graphene and the heterostructure), suggesting a breakdown of the adiabatic Born-Oppenheimer approximation. Moreover, charge imbalance and renormalization of the electron-hole dispersion under the additional influence of the doped functional GQDs is pointing to an asymmetry in conduction and carrier mobility.
UR - http://www.scopus.com/inward/record.url?scp=85130862829&partnerID=8YFLogxK
U2 - 10.1088/1361-6528/ac6c38
DO - 10.1088/1361-6528/ac6c38
M3 - Article
VL - 33.2022
JO - Nanotechnology
JF - Nanotechnology
SN - 0957-4484
IS - 32
M1 - 325704
ER -