Probing the charge transfer and electron-hole asymmetry in graphene-graphene quantum dot heterostructure

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Publikace nespadá pod Ekonomicko-správní fakultu, ale pod Přírodovědeckou fakultu. Oficiální stránka publikace je na webu muni.cz.
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ROY Rajarshi HOLEC David KRATZER Markus MUENZER Philipp KAUSHIK Preeti MICHAL Lukáš KUMAR Gundam Sandeep ZAJÍČKOVÁ Lenka TEICHERT Christian

Rok publikování 2022
Druh Článek v odborném periodiku
Časopis / Zdroj Nanotechnology
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Citace
www https://doi.org/10.1088/1361-6528/ac6c38
Doi http://dx.doi.org/10.1088/1361-6528/ac6c38
Klíčová slova graphene; graphene quantum dots; scanning probe microscopy; charge transfer; ab initio
Popis 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.
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