A multi-layered MoS 2 film was formed on a SiO 2 film by high-temperature sputtering, which is one of the alternative methods of Si LSI technology. It was found that the carrier density of a sputter-deposited MoS 2 film is 1000 times smaller than that of an exfoliated one. By sputtering, two different orientations, namely a layer lateral to a SiO 2 /Si substrate and a layer perpendicular to the substrate, were formed. The lateral layer showed a lower carrier density than the perpendicular layer because of the decrease in the number of sulfur vacancies, as commonly discussed in several research studies. However, the vacancies are not sufficient for describing this significant reduction in carrier density. It is considered that a sodium ion functioning as an interface trapped charge is one of the main origins of carriers. Sputtering, which enables us to determine the sodium contamination level, can be seen as appropriate for reducing the carrier density; hence, this method is considered to be efficient in realizing enhancement-mode MoS 2 MOSFETs. In addition, sputtering also enable us to form large-scale MoS 2 films up to a wafer size. Therefore, a sputterdeposited MoS 2 film is a promising material for post-silicon devices.

The effects of lanthanum incorporation into HfO2 dielectrics were studied using first-principles total energy calculations. The author’s computational result clearly showed that the formation energy of a neutral oxygen vacancy (VO0) in the vicinity of substitutional La atoms at Hf sites is 0.7eV larger than that in pure HfO2, indicating that the concentration of VO0’s is drastically reduced by La incorporation. This effect is understood to be caused by the decrease in the local dielectric constant κL around La atoms due to the strong ionic character of the La–O bond compared to the Hf–O bond.

The electron transport in W/CeOx/SiO2/NiSi2 resistive switching devices fabricated onto a p+-type Si substrate is investigated. It is shown that the structures exhibit bipolar switching with conductance values in the low resistance state (LRS) close to integer and half integer values of the quantum unit G0 = 2e2/h, e and h being the electron charge and Planck constant, respectively. This behavior is consistent with the so-called nonlinear conduction regime in quantum point-contacts. A simple model for the LRS current-voltage characteristic based on the finite-bias Landauer formula which accounts for the right- and left-going conduction modes dictated by the constriction’s cross-section area and the voltage drop distribution along the filamentary path is reported.

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We have demonstrated DNA handling with micromachined nanotweezers that consist of a pair of opposing nanoprobes and integrated thermal expansion microactuators for changing the probe gap. The probe tips coated with a thin Al layer were dipped into a droplet of a solution containing lambda-DNA molecules labeled with fluorescence dye, and then an ac electric field was applied between probes for several seconds. DNA molecules were then captured between the probe tips and retrieved from the solution to the air. The DNA capture between the probe tips could be performed more successfully on the droplet surface than in the underwater region. We also conducted an observation of the retrieved DNA molecules by transmission electron microscope and found that the thickness of the retrieved DNA molecules under the condition of this experiment was approximately 21 nm when the time of the applied ac power (1 MHz, 20 Vpp) was 20 s.