Forces and electronic transport in a contact formed by a graphene tip and a defective MoS 2 monolayer: a theoretical study

D Di Felice 1 Y Dappe 1 C. Gonzalez 1
1 GMT - Groupe Modélisation et Théorie
IRAMIS - Institut Rayonnement Matière de Saclay, SPEC - UMR3680 - Service de physique de l'état condensé
Abstract : A theoretical study of a graphene-like tip used in atomic force microscopy (AFM) is presented. Based on first principles simulations, we proved the low reactivity of this kind of tip, using a MoS2 monolayer as the testing sample. Our simulations show that the tip-MoS2 interaction is mediated through weak van der Waals forces. Even on the defective monolayer, the interaction is reduced by one order of magnitude with respect to the values obtained using a highly reactive metallic tip. On the pristine monolayer, the S atoms were imaged for large distances together with the substitutional defects which should be observed as brighter spots in non-contact AFM measurements. This result is in contradiction with previous simulations performed with Cu or Si tips where the metallic defects were imaged for much larger distances than the S atoms. For shorter distances, the Mo sites will be brighter even though a vacancy is formed. On the other hand, the largest conductance value is obtained over the defect formed by two Mo atoms occupying a S divacancy when the half-occupied p y -states of the graphene-like tip find a better coupling with d-orbitals of the highest substitutional atom. Due to the weak interaction, no conductance plateau is formed in any of the sites. A great advantage of this tip lies in the absence of atomic transfer between the tip and the sample leading to a more stable AFM measurement. Finally, and as previously shown, we confirm the atomic resolution in a scanning tunneling microscopy simulation using this graphene-based tip.
Type de document :
Article dans une revue
Nanotechnology, Institute of Physics, 2018, 29 (22), 〈10.1088/1361-6528/aab5fc〉
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Contributeur : Dominique Girard <>
Soumis le : mardi 11 septembre 2018 - 15:13:38
Dernière modification le : jeudi 13 septembre 2018 - 01:10:22

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D Di Felice, Y Dappe, C. Gonzalez. Forces and electronic transport in a contact formed by a graphene tip and a defective MoS 2 monolayer: a theoretical study. Nanotechnology, Institute of Physics, 2018, 29 (22), 〈10.1088/1361-6528/aab5fc〉. 〈hal-01872025〉



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