Random Telegraph Noise in Individual Single-walled Carbon Nanotubes
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Random Telegraph Noise in Individual Single-walled Carbon Nanotubes SungHo Jhang, SangWook Lee, DongSu Lee, Eleanor E. B. Campbell1, Siegmar Roth2, and YungWoo Park School of Physics, Seoul National University, Seoul, 151-747, Korea 1 Department of Experimental Physics, Gothenburg University and Chalmers University of Technology, SE-412 96 Gothenburg, Sweden 2 Max-Planck Institute for Solid State Research, D-70569 Stuttgart, Germany ABSTRACT The switching of resistance between two discrete values, known as random telegraph noise (RTN), was observed in individual single-walled carbon nanotubes (SWNTs). The RTN has been studied as a function of bias-voltage and gate-voltage as well as temperature. By analyzing the features of the RTN, we identify three different types of RTN existing in the SWNT related systems. While the RTN can be generated by the various charge traps in the vicinity of the SWNTs, the RTN for metallic SWNTs is mainly due to reversible defect motions between two metastable states, activated by inelastic scattering with electrons.
INTRODUCTION Single-walled carbon nanotubes (SWNTs) have been widely investigated to use them in nanoelectronics, based on their remarkable electrical properties [1]. However, a report on the noise properties of SWNTs manifests a barrier in their low-noise electronic applications. According to Collins et al. [2], SWNT conductors exhibit 1 / f excess noise four to ten orders of magnitude larger than that observed in more conventional conductors at room temperature. The understanding of their noise mechanism is necessary to suppress the excess noise and characterize the performance of nanotube nanoelectronic devices. Up to now, many researches on the noise properties of carbon nanotubes confirmed the dominance of 1 / f noise for the low frequency range (f < 1 KHz) [2-8]. The various charge traps in the vicinity of carbon nanotubes are expected to play a role in the observed 1 / f noise, since the nanotubes are prepared on the dielectric substrates. However, the noise behaviors in Coulomb-blockade regime studied for a multi-walled carbon nanotube (MWNT) single-electron-transistor (SET) could not be explained by the charge fluctuations alone as pointed out in ref. 3. Also, the similar experiment performed on a SWNT-SET device [5] showed a complete deviation from the gain dependence of the noise,
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the typical sign of the noise caused by the charge fluctuations [9]. Moreover, Nygård and Cobden reported no consistent improvement of the noise in their etched devices, where the nanotubes were suspended over the substrates [10]. The origin of the excess noise in nanotubes, therefore, should be attributed to the other mechanism than background charge fluctuations. Recently, the random switching of resistance between two discrete values, known as the random telegraph noise (RTN), was observed in individual metallic SWNTs [11]. Since 1 / f noise is generally regarded as a superposition of such two-level resistance-fluctuations, the study of the RTN provides a powerful
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