Navegando por Autor "Araujo, Karolline Aparecida de Souza"
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Item Charge transfer between carbon nanotubes on surfaces.(2015) Araujo, Karolline Aparecida de Souza; Barboza, Ana Paula Moreira; Fernandes, Thales Fernando Damasceno; Shadmi, Nitzan; Joselevich, Ernesto; Mazzoni, Mário Sérgio de Carvalho; Neves, Bernardo Ruegger AlmeidaThe charge transfer between neighboring single-walled carbon nanotubes (SWNTs) on a silicon oxide surface was investigated as a function of both the SWNT nature (metallic or semiconducting) and the anode/cathode distance using scanning probe techniques. Two main mechanisms were observed: a direct electron tunneling described by the typical Fowler–Nordheim model, and indirect electron transfer (hopping) mediated by functional groups on the supporting surface. Both mechanisms depend on the SWNT nature and on the anode/cathode separation: direct electron tunneling dominates the charge transfer process for metallic SWNTs, especially for large distances, while both mechanisms compete with each other for semiconducting SWNTs, prevailing one over the other depending on the anode/cathode separation. These mechanisms may significantly influence the design and operation of SWNT-based electronic devices.Item Electro-optical interfacial effects on a graphene/π-conjugated organic semiconductor hybrid system.(2018) Araujo, Karolline Aparecida de Souza; Cury, Luiz Alberto; Matos, Matheus Josué de Souza; Fernandes, Thales Fernando Damasceno; Cançado, Luiz Gustavo de Oliveira Lopes; Neves, Bernardo Ruegger AlmeidaThe influence of graphene and retinoic acid (RA) – a π-conjugated organic semiconductor – interface on their hybrid system is investigated. The physical properties of the interface are assessed via scanning probe microscopy, optical spectroscopy (photoluminescence and Raman) and ab initio calculations. The graphene/RA interaction induces the formation of a well-organized π-conjugated self-assembled monolayer (SAM) at the interface. Such structural organization leads to the high optical emission efficiency of the RA SAM, even at room temperature. Additionally, photo-assisted electrical force microscopy, photo-assisted scanning Kelvin probe microscopy and Raman spectroscopy indicate a RA-induced graphene doping and photo-charge generation. Finally, the optical excitation of the RA monolayer generates surface potential changes on the hybrid system. In summary, interface-induced organized structures atop 2D materials may have an important impact on both design and operation of π-conjugated nanomaterialbased hybrid systems.Item Room temperature observation of the correlation between atomic and electronic structure of graphene on Cu(110).(2016) Silva, Thais Chagas Peixoto; Cunha, Thiago Henrique Rodrigues da; Matos, Matheus Josué de Souza; Reis, Diogo Duarte dos; Araujo, Karolline Aparecida de Souza; Malachias, Angelo; Mazzoni, Mario Sergio de Carvalho; Ferlauto, Andre Santarosa; Paniago, Rogério MagalhãesIn this work we have used atomically-resolved scanning tunneling microscopy and spectroscopy to study the interplay between the atomic and electronic structure of graphene formed on copper via chemical vapor deposition. Scanning tunneling microscopy directly revealed the epitaxial match between a single layer of graphene and the underlying copper substrate in different crystallographic orientations. Using scanning tunneling spectroscopy we have directly measured the electronic density of states of graphene layers near the Fermi level, observing the appearance of a series of peaks in specific cases. These features were analyzed in terms of substrate-induced perturbations in the structural and electronic properties of graphene by means of atomistic models supported by density functional theory calculations.