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We propose and demonstrate the "defect-induced plasma process" for the fabrication of the room-temperature-operated carbon nanotube single-electron transistors (CNT-SETs) with the SiO2 protection films on the CNT channels. After introducing of defects in the CNT channels by O2 plasma irradiation through the SiO2 protection films, multi-quantum dots were fabricated in the CNT channels. The electrical properties of the CNT-SETs suggested that the oscillation in the drain currents as a function of the gate voltage was observed at room temperature, as a result of the Coulomb blockade effect. Moreover, we report that the yield of the CNT-SETs depended on the thickness of the SiO2 protection films on the CNT channels for the purpose of obtaining a high yield of CNT-SETs. The results indicate that the high yield of the CNT-SETs is as high as approximately 35% when the SiO2 protection film thickness is 60 nm. Consequently, the defect-induced plasma process is useful for obtaining the high yield efficiency of CNT-SETs operating at room temperature.

Using the patterned chemical catalyst, the position of the carbon nanotube was successfully controlled. Using this carbon nanotube as a channel, the single electron transistor was fabricated. The defects in the carbon nanotube formed spontaneously quantum dots with the size of ~1 nm. The single electron transistor showed the room-temperature Coulomb diamond characteristics with an ultra-high Coulomb energy of 5000 K.

The new fabrication process for a carbon nanotube (CNT) single-electron transistor (SET) operated at room temperature was proposed using La(NO3)3. The carbon nanotube reacts with oxygen included in La(NO3)3 at high temperature and the defects that worked as tunnel junctions were introduced. For consistency CNT-SET shows Coulomb oscillation and Coulomb diamond characteristics at 300 K. From the simulation, it was found that the newly proposed process introduced three effective defects into CNT, and CNT-SET worked as two islands SET.

The control of the growth direction of a carbon nanotube was accomplished by applying an electric field during the growth of the carbon nanotube. The effects of two types of applied bias, one is a constant DC bias, and the other is a ramp bias, on the control of the growth direction were examined. By maintaining a constant DC bias we could control the growth direction of the carbon nanotube, however, the bridging ratio between the two electrodes was as small as 35%. We suppose that this low bridging ratio may be caused by the etching effect of hydrogen. When a ramp bias was applied, bridging ratio tended to increase with the slope of ramp bias. Under optimal conditions, the bridging ratio reached a value as high as 95%.

We demonstrate that a non-contact atomic force microscope (AFM) can be used to cut and nick carbon nanotubes (CNTs) by applying negative bias to the metal-coated AFM tip when it is very close to the CNT. The voltage needed to cut the CNT completely varied from -8 to -15 V, while the nicking voltage ranged from -6 to -8 V. This technique was applied to make a nanoscale single CNT device. Unwanted CNTs were cut first to leave only one CNT connecting the electrodes. Finally, tunneling barriers defined by two small nicks were created on the CNT to fabricate a single electron transistor. The final device shows Coulomb oscillation and Coulomb diamond characteristics at room temperature.

The effect of the selective adsorption of pig serum albumin as an antigen on the electrical properties of a carbon nanotube channel field effect transistor on which anti-pig serum albumin was immobilized as an antibody by physisorption in phosphate buffer solution has been investigated. We have succeeded in real-time detection of the adsorption of pig serum albumin on anti-pig serum albumin as a decrease in the conductance of the carbon nanotube channel field effect transistor, by a label-free process.

The air stable n-type carbon nanotube channel filed effect transistor (CNT-FET) with the top gate structure was successfully fabricated using the silicon nitride gate insulator deposited by the thermal chemical vapor deposition. The effects of the silicon nitride insulator on the electrical properties of the CNT-FET have been investigated. The p-type characteristics of the CNT-FET can be converted to the n-type characteristics in high yield of 90% only by depositing the silicon nitride insulator. The drain current is as high as few µA order. The n-type top gate CNT-FET stably operated even in ambient air.

We have succeeded in observing the single hole transistor characteristics in position-controlled grown carbon nanotubes (CNTs) with artificial defects formed by a chemical process. Coulomb blockade characteristics were observed around the hole depletion region even at room temperature. At a low temperature, however, the Coulomb blockade characteristics were observed both in hole and electron transport regions.