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We fabricate the graphene/h-BN stacked mechanical resonator and investigate the gate voltage dependence of the resonance property of the graphene/h-BN mechanical resonator. The mode splitting on the resonance of the stacked resonator is found at a specific gate voltage region, where the frequency difference of two peaks corresponding to two modes showed the square of gate voltage dependence. This implies that the mode splitting observed is that the electrostatic attraction on the graphene layer influences the interlayer interaction of graphene and h-BN. The energy transfer between the two resonance states was also observed.

An atomically thin MoS2 field-effect transistor (FET) is expected as an ultrathin photosensor with high sensitivity. However, a persistent photoconductivity phenomenon prevents high-speed photoresponse. Here, we investigate the photoresponse of a MoS2 FET with a thin Al2O3 buffer layer on a SiO2 gate insulator. The application of a 2-nm-thick Al2O3 buffer layer greatly improves not only the steady state properties but also the response speed from 1700 to 0.2 s. These experimental results are well explained by the random localized potential fluctuation model combined with the model based on the recombination of the bounded electrons around the trapped hole.

Magnetic properties of an individual Fe-alloy-capped nanotube synthesized by catalytic chemical vapor deposition have been investigated for use as probes for magnetic force microscopy (MFM). The remanent magnetization for one unit volume of the Fe-alloy-capped nanotube is 297 emu/cm3 which is comparable to that of a conventional MFM tip. The MFM measurements have been performed using a combination of the Fe-alloy-capped nanotube tip and a frequency modulation detection system in order to improve the sensitivity of MFM.

We investigate the pressure dependence of transfer characteristics of suspended single-walled carbon-nanotube field-effect transistors. We find that the gate bias around the charge neutral point with low drain current is appropriate for gas sensing application, while the high gate bias condition with high drain current that induces Joule heating in the suspended region for the desorption of the adsorbed molecules is preferable for the vacuum gauge application based on the heat exchange surrounding gas molecules, where the temperature at the suspended channel is investigated based on the simple one-dimensional heat transport model. We also revealed that the pressure dependence of the channel conductance at the gate bias around the charge neutral point can be explained by the Langmuir isotherm.

We investigated the bimaterial effect on a multiwall carbon nanotube (CNT) cantilever by means of a photothermal actuation method toward sensitivity enhancement for calorimetry. The coating of a 10-nm-thick Ti layer on top of the CNT cantilever of 50 nm diameter successfully enhanced the photothermal vibration amplitude by 10–50 times. This implies that the expected resolution for the heat capacity measurement is as high as ∼0.1 fJ/K on the base of a simple lumped model for the photothermally excited Ti-coated CNT cantilever.

We have investigated the release of a stuck carbon nanotube cantilever beam by molecular dynamics simulation toward nanorelay applications. We have demonstrated that the successful release of a nanotube arm from the stuck state at room temperature can be realized by the application of a resonant external vibration to the nanotube cantilever beam. The release of the stuck nanotube cantilever beam was well explained by the thermal activation model with a barrier height of the van der Waals interaction between the nanotube arm and the counter electrode.

We have proposed the application of the surface plasmon resonance method to the measurement of the optical response of graphene thin films. A surface plasmon is a coherent electron oscillation that is excited at the interface between two materials when p-polarized light is incident. We revealed that the excitation angle shifts by about 0.1° in the case of monolayer graphene compared with the bare Au surface as determined by calculation. We also identified angle shifts of the excitation conditions for surface plasmon experimentally when graphene thin films fabricated by filtration exist on the Au surface, corresponding to 5–8 layers of graphene, as determined by the calculation.

We demonstrated single-walled carbon nanotube aggregation at electrode edges by local electric field enhancement by a focused laser irradiation. It was revealed that the formation of nanobubbles and their induced fluid motion play an important role in carrying nanotubes to the electric field enhancement region around the laser irradiation spot from the laser power dependence of the aggregation on electrode edges. Furthermore, we found that metallic nanotubes preferentially aggregated near irradiation spots by the investigation of the laser irradiation time dependence of the aggregation. This technique is useful for manipulating and bridging nanotubes between electrodes for device applications.

We have investigated the temperature dependence of cantilevered carbon nanotube oscillation in terms of the dissipation mechanism. The temperature dependences of resonant frequency andQfactor could be divided in two parts corresponding to the temperature dependence of Young's modulus at critical temperature. We have revealed that the critical temperature corresponds to the softening temperature of the nanotubes depending on crystallinity. Furthermore, we have pointed out that the temperature dependence ofQfactor at low temperatures mainly comes from the internal loss.

We have investigated the damping effects of gas molecules on the vibration of a carbon nanotube cantilever. An optical detection system to detect the vibration in gaseous molecules was built. The energy loss induced by the gas molecules is proportional to a pressure at 102–104 Pa. At pressures below 10 Pa, the energy loss is negligible compared with the intrinsic loss of the vibration energy for the nanotube. This is because the size of the nanotube is much smaller than the mean free path of the gas molecules.