Effects of Electron Beam in Carbon Nanotube Transistors

This work explores the effects of nano - scale scattering centers on electronic transport behavior in carbon nanotubes. Because of the low dimensionality, the transport physics of a carbon nanotube transistor is fundamentally interesting and possesses significant differences compared to traditional bulk transistors. ln particular, the high sensitivity to an electric field variation allows a carbon nanotube to detect a single trap, leading to Random Telegraph Signals in channel current. lnteraction between traps is observed and analyzed at room temperature; the observation reveals a fine tunability of trap energy levels which is unique in a one dimensional transistor. To study the trap's influence on a carbon nanotube transistor in real time, an electron beam lithography system was modified in order to permit in situ transport measurements. Effects at different irradiation dose levels were studied. lt was found that traps can be induced with low - dose irradiation, causing two - state discrete current noise, while high - dose irradiation can induce a tunnel barrier across a nanotube. The experimental results presented here have broad implications and demonstrate that manipulation of substrate is as important as the channel itself in a nanotube - based transistor.

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