Electrical properties of Pd-contacted single-walled carbon nanotubes: a scanning probe microscopy study
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Electrical properties of Pd-contacted single-walled carbon nanotubes: a scanning probe microscopy study. O. V. Kononenko1, S. I. Bozhko2, V. N. Matveev1,V.T.Volkov1, M. A. Knyazev1, A. I. Il’in1, D. V. Matveev2, Yu. A. Kasumov1, I. I. Khodos1 1 Institute of Microelectronics Technology and High Purity Materials, RAS, 142432 Chernogolovka, Moscow region, Russia 2 Institute of Solid State Physics, RAS, 142432 Chernogolovka, Moscow region, Russia ABSTRACT Pd is widely used in producing electrodes to single-walled carbon nanotubes (SWNT). However up to now its ability to form ohmic contacts to SWNTs was not employed in scanning probe microscopy (SPM). Here we present a study of SWNTs with Pd electrodes by SPM using Pd-coated tips. SWNTs were selectively grown on oxidized silicon substrates by low pressure CVD method. Pd electrodes were prepared to SWNTs to fabricate two terminal structures for SWNTs resistance measurements. It is shown that SPM Kelvin mode is a reliable technique for SWNT detection on insulating substrate. Contact potential difference between Pd electrode and SWNT is measured using the Kelvin mode.
INTRODUCTION Single-walled carbon nanotubes (SWCNTs) have attractive properties for using as building blocks for future nanoelectronics devices due to the outstanding electrical, mechanical, physical, and optical properties of the typical one-dimensional (1D) materials. In recent years, many studies have been performed on single-walled carbon nanotubes for their promising applications in future nanoelectronics and nanodevices such as SWCNT field effect transistors (FET’s) [1–3], logic devices [4–6], resonators [7], field emitters [8,9] and sensors [10]. Catalytical chemical vapor deposition (CVD) [11] is one of the main techniques of carbon nanotubes synthesis and is very important for many applications [12, 13]. Previously we reported on a new technique for CVD synthesis of carbon nanotubes under very low pressure of acetylene (about 0.4 torr) without any gas flow. TEM observation and electron diffraction patterns, Raman spectroscopy and electron transport measurements showed the good quality of the obtained nanotubes [14]. Selective growth of CNTs on substrates is highly desirable for fabrication of nanoelectronic devices with the aid of standard photo- and electron beam lithograpgy. It is known that electronic properties of carbon nanotubes depend on their structure. In order to use nanotubes to create electronic devices, it is necessary to control their structural parameters. Diameter of nanotubes is one of the important parameters. It depends on the diameter of a catalytic particle on which the nanotube grows. By means of various methods of deposition (electron beam evaporation, rf-sputtering, laser beam evaporation) and processing (for example, annealing) of the catalytic particles it is possible to vary the diameter distribution of catalytic particles, and thus to control the diameters of produced nanotubes. An attractive method of measuring surface potential is the scanning Kelvin force m
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