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Improved lateral resolution in Kelvin Probe Force Microscopy by using silicon tips covered by Au nanoparticles

AutorHormeño, Silvia ; Penedo García, Marcos ; Briones Fernández-Pola, Fernando ; Luna, Mónica
Fecha de publicaciónsep-2012
CitaciónCongreso Fuerzas y Tunel (2012)
ResumenKelvin probe force microscopy ( KPFM) is a powerful atomic force microscope (AFM)-based technique to meas ure the local variations of surface potential at the nanoscale. It operates by detecting the difference of the work function between a fixed substrate and a conducting movable probe. By modulating the applied potent ial on the probe until the electric force between sample and tip is extinguish ed, it is possible to deter mine the local potential of the surface. KPFM has been extensively us ed to characterize the electrical properties of a wide variety of samples, from semiconductors to biomolecules. As KPFM spatial resolution is intrin sically limited by the long range of the electrostatic interaction, many contri butions on this technique are aimed to improve this feature. Some of them include operating in high vacuum and the development of specialized probes to operate in ambient conditions as, for example, the use of carbon nanotubes or coaxial AFM probes that are electrically shielded everywhere exc ept the very end of the tip. Here we present the use of standar d silicon tips modified by the deposition of gold nanoparticl es. These tips have recent ly shown to improve the aspect ratios and spatial resolution of AFM images. The silicon tips are modified by deposition of nan oclusters of nominal diam eter of 2-3 nm under ultrahigh vacuum conditions using an ion cluster source. In an attempt to extend this enhancement of the resolution and sensitivity to the electrical measurements under ambient conditions, we have performed a KPFM analysis of several samples that include Au and Ag nanoparticles , graphene flakes on silicon dioxide, single-wall carbon nanotubes and double-stranded DNA molecules. The results are compared with similar measurements performed with conventional metallic tips (PtIr5 coated tips). We show that both, topography and surface potent ial images present evid ent improvements when recorded with Au-nanoparticle modified tips
DescripciónPóster presentado en el Congreso Fuerzas y Tunel, celebrado en San Lorenzo de El Escorial del 12 al 14 de septiembre de 2012.
Aparece en las colecciones: (IMN-CNM) Comunicaciones congresos
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