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Congenital disorders characterized by the quantitative and qualitative reduction in the number of functional nephrons are the primary cause of chronic kidney disease (CKD) in children. We aimed to describe the alteration of urinary extracellular vesicles (uEVs) associated with decreased renal function during childhood. By nanoparticle tracking analysis and quantitative proteomics, we identified differentially expressed proteins in uEVs in bilateral renal hypoplasia, which is characterized by a congenitally reduced number of nephrons. This expression signature of uEVs reflected decreased renal function in CKD patients by congenital anomalies of the kidney and urinary tract or ciliopathy. As a proof-of-concept, we constructed a prototype ELISA system that enabled the isolation of uEVs and quantitation of expression of molecules representing the signature. The system identified decreased renal function even in its early stage. The uEVs signature could pave the way for non-invasive methods that can complement existing testing methods for diagnosing kidney diseases.

We have developed an advanced microintaglio printing method for fabricating fine and high-density micropatterns and applied it to the microarraying of RNA molecules. The microintaglio printing of RNA reported here is based on the hybridization of RNA with immobilized complementary DNA probes. The hybridization was controlled by switching the RNA conformation via the temperature, and an RNA microarray with a diameter of 1.5 µm and a density of 40,000 spots/mm(2) with high contrast was successfully fabricated. Specifically, no size effects were observed in the uniformity of patterned signals over a range of microarray feature sizes spanning one order of magnitude. Additionally, we have developed a microintaglio printing method for transcribed RNA microarrays on demand using DNA-immobilized magnetic beads. The beads were arrayed on wells fabricated on a printing mold and the wells were filled with in vitro transcription reagent and sealed with a DNA-immobilized glass substrate. Subsequently, RNA was in situ synthesized using the bead-immobilized DNA as a template and printed onto the substrate via hybridization. Since the microintaglio printing of RNA using DNA-immobilized beads enables the fabrication of a microarray of spots composed of multiple RNA sequences, it will be possible to screen or analyze RNA functions using an RNA microarray fabricated by temperature-controlled microintaglio printing (TC-µIP).

Arraying individual extracellular vesicles (EVs) on a chip is expected one of the promising approaches for investigating their inherent properties. In this study, we immobilized individual EVs on a surface using a nanopatterned tethering chip-based versatile platform. A microfluidic device was used to ensure soft, reproducible exposure of the EVs over the whole chip surface. The device is incorporated with a high-density nanoarray chip patterned with 200-nm diameter nanospots composed of polyethylene glycol (PEG)-lipid conjugate brushes. We present a procedure adopted for fabricating high-density PEG-lipid modified nanospots (200 nmϕ, 5.0 × 105 spots/mm2 in 2 × 2 mm2 area). This procedure involves nanopatterning using electron beam lithography, followed by multistep selective chemical modification. Aqueous treatment of a silane coupling agent, used as a linker between PEG-lipid molecules and the silicon surface, was the key step that enabled surface modification using a nanopatterned resist film as a mask. The nanoarray chip was removed from the device for subsequent measurements such as atomic force microscopy (AFM). We developed a prototype device and individually immobilized EVs derived from different cell lines (Sk-Br-3 and HEK293) on tethering nanospots. We characterized EV's morphology using AFM and showed the possibility of evaluating the deformability of EVs using the aspect ratio as an indicator.

On the ferromagnetic-film-coated carbon nanotube for a magnetic force microscope (CNT-MFM) probe, the stability of the magnetic structure in an external magnetic field was investigated using a three-dimensional micromagnetic simulation. When a magnetic field was applied along the longitudinal direction, in the direction opposite that of the magnetization of the probe, the direction of the magnetic moments of the probe remained the same up to −200 mT and then reversed all at once. When a magnetic field was applied along horizontal direction, the direction of the magnetic moments gradually tilts with increasing field. MFM observations seem to be possible for magnetic fields up to 100 ∼ 150 mT, judging from the magnetic structure of the probe. In contrast, the magnetic structures of pyramidal probes show vortex-like magnetic structure and low tolerance to an external magnetic field. The CNT-MFM probe is relatively robust under an external magnetic field due to the strong shape anisotropy attributed to its cylindrical shape.

Graphene and graphite synthesis of uniform films is becoming routine, so now efforts are turning to grow specific patterns or complex structures. More research is needed with regard to the practical aspects of the growth of graphene layers, especially as it relates to self-assembled structures. We used gallium-catalyzed thermal decomposition of silicon carbide to understand spatially confined growth. Growing graphene layers push on a large step in hard silicon carbide (SiC) with significant force, as observed by high-resolution transmission electron microscopy of film cross sections. Alternatively multiple graphitic layers can grow into disks embedded in silicon carbide if the crystal is heated above the transition to plastic deformation. Euler buckling appears to limit the size and deformation of the silicon carbide crystal to produce graphitic flakes with an oriented hexagonal shape. These results illustrate the effect of the mechanical force of growing graphene in confined spaces: the growing graphene ...

The advantage of the CoFe-coated carbon nanotube (CNT) probes in a magnetic force microscope (MFM) is verified on in-plane magnetized soft magnetic materials. CoFe-coated CNT, standard and low-moment MFM probes were used to observe closure domains in square and rectangular Permalloy elements. The perturbative effect of the CNT–MFM probe was far less than that of a standard MFM probe. Domain walls were clearly observed as a pair of dark and bright lines which was in agreement with the micromagnetic simulations. The vortex core was also clearly observed using the CNT–MFM probes.

We systematically investigated thickness and magnetization variations of the domain structures of MnAs films on GaAs(0 0 1) using magnetic force microscopy (MFM) at room temperature. The observed thickness range is from 5 to 500 nm. The magnetic domain structures drastically change with increasing thickness because of the existence of the thickness-dependent periodic ridge-groove structure. The domain structures also depend on the magnetization histories. The MnAs films with the thickness of less than 50 nm have no groove structure and the single magnetic domain is realized at the remanent state. In the thickness more than 100 nm, on the other hand, the groove structures of paramagnetic β-MnAs appear. The complex magnetic domain structures of MnAs films result from the paramagnetic groove structures, the uniaxial anisotropy and weak perpendicular anisotropy.

Humidity effects on nano-oxidation are investigated using a dynamic force microscope in the humidity range of 30–60%. Oxide size and detected faradaic current increased with relative humidity and applied voltage. The aspect ratios of fabricated oxides at various humidities are approximately of the same magnitude. Scanning probe microscope nano-oxidation in the dynamic mode is less subject to the relative humidity than that in the contact mode.

The dopant type and carrier concentration in a patterned semiconductor sample with three different doping regions were measured by scanning nonlinear dielectric microscope (SNDM). SNDM is used in the way of a scanning capacitance microscopy (SCM) with a new detection mechanism based on frequency detection. The topographic, pn-distribution and the carrier concentration images of a patterned semiconductor sample were measured at the same time. In concurrence with a demonstration of the SNDM-SCM measurements, the influence of an adsorbed water layer on measurements is evaluated in the vacuum and in the air over a relative humidity (RH) range of 20 to 80%. Adverse affects on capacitance measurements due to the variation in RH are revealed. [DOI: 10.1380/ejssnt.2006.454]

In the nanocrystalline Fe78Si10B12 thin film, a weak dense stripe domain structure is observed. Out-of-plane anisotropy accounts for the observed domain structure. Perpendicular shape anisotropy due to the formation of the island-like configuration by the annealing treatment and magnetocrystalline anisotropy due to the strong α-Fe(Si) (1 1 0) texture are considered to be the origin of the perpendicular anisotropy. A metastable domain structure, which is the superimposition of the fine dense stripe domain structures onto the in-plane wide basic domains, was also observed in the as-annealed sample. The metastable domain structure turns to a stable single-domain state after magnetization.

Ferromagnetic-film-coated carbon nanotube (CNT) probes were employed in a magnetic force microscope (MFM) observation. We succeeded in making a uniform ferromagnetic film on the CNT probes by improving the coating process and selecting materials. The performance of the CoFe-coated CNT probe was evaluated in ultra-high-density perpendicular magnetic storage media with densities from 600 to 1100?k flux changes per inch (FCI). The magnetic domain structure of the magnetic storage media was clearly observed up to 1100?kFCI. The ultimate lateral resolution of the newly developed MFM probes is down to about 10?nm, which exceeds the bit length of a magnetic recording with a density of Tbit?inch?2.

Nanometer-scale structures were fabricated by anodic oxidation using scanning probe microscopes on thin-films of various 3d-metal compounds and alloys on GaAs, such as MnAs, MnSb, Cr2O3, CoCr and NiFe. Material variation advances the developments in nano-fabrication by scanning probe microscope. Comparing the oxidation conditions, new methodology for fabrication of nano-devices is explored.

Scanning probe microscope nano-oxidation is carried out on H-passivated Si(0 0 1) surfaces using a humidity control atomic force microscope (AFM) in contact and dynamic modes. To achieve high precision nano-oxidation at large scale, the original tube-scanner-based AFM unit is modified: horizontal movement of the whole sample block (sample stage and the scanner) is operated by an additional XY piezo stage, whilst its vertical movement is controlled by a piezo tube-scanner. The high linearity of the horizontal movement is demonstrated by high resolution oxide patterns which are fabricated after the instrumental modification using standard AFM cantilevers and a modified AFM cantilever with an added carbon nano-tube on tip.

A comprehensive analysis of the electrical current passing through the tip-substrate junction during oxidation of silicon by scanning probe microscopy (SPM) is presented. This analysis of experimental results under dc-bias conditions resolves the role of electronic and ionic contributions, especially for the initial stages of the reaction, determines the effective contact area of the tip-substrate junction, and unifies the roles of space charge and meniscus formation. In Part I of this work, we demonstrate that SPM oxidation is governed by a maximum charge density generated by electronic species within the junction at the onset of the oxidation process. Excess charge is channeled into lateral diffusion, keeping the charge density within the reaction zone constant and reducing the aspect ratio of the resulting oxide features. A uniform charge density implies that SPM oxides contain a fixed defect concentration, in accordance with the space-charge model. The effective (electrical) thickness of SPM oxides de...

A comprehensive analysis of the electrical current passing through the tip-substrate junction during oxidation of silicon by scanning probe microscopy (SPM) is presented. This analysis identifies the electronic and ionic contributions to the total current, especially at the initial stages of the reaction, determines the effective contact area of the tip-substrate junction, and unifies the roles of space charge and meniscus formation. In this work, we concentrate on noncontact SPM oxidation. We analyze simultaneous force-distance and current-distance curves to demonstrate that total current flow during noncontact oxidation is significantly less for noncontact mode than for contact oxidation, although the resulting oxide volume is nearly identical. Ionization of water layers and mobile charge reorganization prior to and following meniscus formation is also shown to alter the tip-substrate capacitance and, therefore, the bending of the SPM cantilever.

Carbon nanotube-attached atomic force microscope probes were successfully used without nanotube bending to make simultaneous precision nano-oxidation and faradaic current measurements in the dynamic mode. Probe oxidation on H-passivated Si(001) surfaces was carried out by two methods involving vector-scan and raster-scan with a much higher resolution and precision compared to the nanofabrication by standard cantilevers. Faradaic current of the order of a sub-picoampere was detected during nano-oxidation using a carbon nanotube probe, accurately reflecting the subtle difference in the oxidation reaction. The minute current detection through the AFM tip is sensitive enough for the detection of very thin oxides and small-sized features. The dimension of the meniscus during nano-oxidation, which is indispensable for establishing the mechanism model, was evaluated, based on the in situ faradaic current detection and edge broadening.

Smooth Fe78Si10B12 thin films were prepared by r.f. sputtering with the very slow deposition rate of 0.59 nm/min. The as-deposited films were not fully amorphous, instead α-Fe(Si) nanocrystallites were found to be embedded in the amorphous matrix. The saturation magnetostriction λs of the as-deposited film is about 6.5 × 10−6. After annealing at 540 °C for 1 h in an ultrahigh vacuum (4.5 × 10−5 Pa), the fraction of α-Fe(Si) crystalline phase largely increased, and correspondingly the λs decreased to 4.5 × 10−7. Ripple domain structures were observed in the as-deposited film, while dense stripe domains were observed in the annealed sample, characterized by a very narrow domain width of 80 nm. (1 1 0) texture and island-like configuration of α-Fe(Si) nanocrystallites formed by the annealing treatment are responsible for the perpendicular anisotropy. For the as-deposited film, the magnetization curves increased linearly with the increase of the magnetic field, and showed the very small hysteresis. On the other hand, the annealed sample clearly showed a very steep jump near the origin, which is due to the switch process of the dense stripe domain.

Strong magnetic poles at characteristic rectangular defects have been observed using a magnetic force microscope on a MnAs(1 1 0 0) thin film with the thickness of 30 nm. The MnAs thin film was epitaxially grown on a GaAs(0 0 1) substrate. The magnetic poles were in one-arranging direction, being independent of the magnetization direction of the film. The poles were pinned at the edges of the rectangular defects until just below the Curie temperature, and formed a stable magnetic-field loop on the MnAs surface. The stability of the magnetic pole pinning shows the distinctive feature of the magnetic domain structure on the surface with a strong anisotropy, which was built in the heterostructure of MnAs and GaAs.

Type of conductively and carrier concentration of a semiconductor sample with three different dopant regions were measured by scanning nonlinear dielectric microscope (SNDM). It is an application of SNDM in to scanning capacitance microscopy with a new detection mechanism that is based on frequency detection. In principle, SNDM includes the SCM function; it is possible to measure not only the conductive type distribution as a conventional SCM, but also the carrier concentration distribution at the same time. As a demonstration, the influence of an adsorbed water layer on the measurements of a semiconductor sample is observed.

The faradaic current during anodic oxidation has been detected using an atomic force microscope with intent to study the meniscus formation process and the oxidation mechanism. The faradaic current is of the order of pA for a Si sample, which is at the same level as the leakage current noise; there are problems in detecting, such as sensitivity limits and poor reproducibility. These problems occurred due to high humidity. We could overcome these problems by hermetically sealing the entire electronic parts in the unit to avoid the humidity effects and achieved the detection of a minute current of the sub-pA order even at high humidity.

The effect of humidity on the nano-oxidation of p-Si(0 0 1) using an atomic force microscope is systematically studied at the relative humidity from 40% to 80%. Nanometer scale structures are fabricated at various relative humidities, applied voltages, exposure times and tip speeds. The size and shape of the fabricated oxide and contribution of the ionic diffusion to the process changed depending on the relative humidity. It was proved that the humidity is a noteworthy parameter for nano-oxidation and needs more careful consideration on equal terms with the oxidation voltage. The first systematic and fundamental information of the humidity effects on the process over a wide humidity range is provided for further study on meniscus formation.

We investigate adsorbed Si atoms on the Si(1 1 1)7 × 7 surface deposited from an scanning tunneling microscope (STM) tip. In our experiments at room temperature, two types of Si adsorbates on the surface are observed, “staying” Si adsorbate that remains at the same position, and “diffusing” Si one that is detected as a noise-like feature on an STM image. Molecular orbital calculations are performed to distinguish difference of these Si adsorbates. Stable positions, transition states, diffusion barriers and electron density iso-surfaces for extra Si atoms on Si cluster models are obtained. From these results, we propose new assignments to these Si adsorbates: the staying and diffusing Si adsorbates correspond to two Si atoms and a single Si atom, respectively.

We have investigated magnetic domain structures of MnAs thin films grown on GaAs substrates by a magnetic force microscope. Weobserved, by an atomic force microscope, rectangular defects along GaAs [110] direction which disperse randomly on the surface of MnAs/GaAs (001). The Curie temperature of MnAs is 45 C, and it is successfully confirmed directly by the variable temperature magnetic forcemicroscope observation. We also investigated magnetic domain structures of MnAs/GaAs (111)B, and no apparent relation was observedbetween the topographic structure and the magnetic domain structure.(Received July 16, 2003; Accepted September 25, 2003)Keywords: MnAs, magnetic force microscopy, phase transition

Detection of pA order minute current by scanning probe microscopy encounters some problems under high humidity atmospheres, such as the increased background level and the poor reproducibility, because of the surface leak current. We were able to overcome these problems by using hermetic sealing and keeping the whole electronics equipment in a humidity-controlled atomic force microscope system. Detection of minute current of sub-pA level has been achieved even under high humidity atmospheres.

A huge positive magnetoresistance effect, more than 10 000% at room temperature, has been discovered in MnSb granular films. Granular films consisting of nanoscale MnSb dots were fabricated on a sulfur-passivated GaAs (0 0 1) substrate by molecular-beam epitaxy, then covered with an Sb thin layer. The MnSb granular films exhibit a strong in-plane anisotropy of the magnetic-field-sensitive current–voltage characteristics. When a constant voltage, above the threshold value, is applied in the [1 1 0] direction of the GaAs (0 0 1) surface, a steep change in the current, which we term magnetoresistive switch (MRS), is driven by the huge magnetoresistance effect under a relatively low magnetic field (less than about 0.2 T ). On the other hand, less than 1% magnetoresistance effect was observed when the voltage was applied in the [1 1 0] direction of the GaAs surface. The origin of the anisotropy is discussed in terms of the microscopic structural anisotropy at the heterointerface.

We demonstrate the possibility in quantifying the Raman intensities for both specimen and substrate layers in a common stacked experimental configuration and, consequently, propose a general and rapid thickness identification technique for atomic-scale layers on dielectric substrates. Unprecedentedly wide-range Raman data for atomically flat MoS(2) flakes are collected to compare with theoretical models. We reveal that all intensity features can be accurately captured when including optical interference effect. Surprisingly, we find that even freely suspended chalcogenide few-layer flakes have a stronger Raman response than that from the bulk phase. Importantly, despite the oscillating intensity of specimen spectrum versus thickness, the substrate weighted spectral intensity becomes monotonic. Combined with its sensitivity to specimen thickness, we suggest this quantity can be used to rapidly determine the accurate thickness for atomic layers.

Dynamic magnetic properties of epitaxial MnAs thin films are studied by means of Brillouin light scattering (BLS). The sharp spectral peaks of the inelastic BLS are observed in room temperature, which are attributed to surface spin waves indicating the long-wavelength collective behavior of ferromagnetic spins. The field dependence of the surface spin-wave frequency is strongly affected by an in-plane angle between the crystal axis and the external field direction in a GaAs(100)/MnAs(-1100) film, which originates from uniaxial magnetic anisotropy parallel to the MnAs[11-20] axis and the modified g value. Significant damping of the spin-wave BLS spectrum is observed with increasing excitation laser power, possibly due to thermal effects.

A faradaic current on the order of a sub-pico-ampere was detected while fabricating two-dimensional oxide nanostructures on H-passivated Si(001) surfaces. The detected faradaic current has been shown to faithfully reflect the degree of probe oxidation with a clear dependence on the variation of voltage and the tip speed. The faradaic current in dynamic mode can serve as a sensitive monitor of the nano-oxidation reaction for implementing precise closed-loop control of the oxide growth.

To understand how nanomechanical stiffness affects metastatic potential, we studied the relationship between cell migration, a characteristic of metastasis, and cell stiffness using atomic force microscopy (AFM), which can measure stiffness (elasticity) of individual living cells. Migration and cell stiffness of three metastatic B16 melanoma variants (B16-F10, B16-BL6, and B16-F1 cells), and also effects of (−)-epigallocatechin gallate (EGCG), were studied using Transwell assay and AFM. Migration of B16-F10 and B16-BL6 cells was 3 and 2 times higher than that of B16-F1 cells in Transwell assay, and cell stiffness determined by AFM was also different among the three variants, although they have similar morphologies and the same growth rates: Means of Young’s modulus were 350.8 ± 4.8 Pa for B16-F10 cells, 661.9 ± 16.5 Pa for B16-BL6 cells, and 727.2 ± 13.0 Pa for B16-F1 cells. AFM measurements revealed that highly motile B16-F10 cells have low cell stiffness, and low motile and metastatic B16-F1 cells have high cell stiffness: Nanomechanical stiffness is inversely correlated with migration potential. Treatment of highly motile B16-F10 cells with EGCG increased cell stiffness 2-fold and inhibited migration of the cells. Our study with AFM clearly demonstrates that cell stiffness is a reliable quantitative indicator of migration potential, and very likely metastatic potential, even in morphologically similar cells. And increased cell stiffness may be a key nanomechanical feature in inhibition of metastasis.

The adsorbates derived from triisopropylindium (TIPIn) on a GaAs(001)-2×4 surface were studied by scanning tunneling microscopy and spectroscopy. TIPIn was adsorbed on a GaAs(001)-2×4 surface dissociatively at room temperature, the characteristic spectrum was detected from each adsorbate of different size. The differences among spectra are discussed qualitatively from energy calculation and comparative experiments, and the change of the electronic states according to size fluctuation is explained by the change of constituents of adsorbates. The smallest adsorbate assigned as In atoms(s) by comparing the electronic states with deposited indium. The mechanism of InAs quantum dots fabrication by the supersonic molecular-beam method is also confirmed at atomic level.

Adsorption and decomposition of trisdimethylaminoarsenic (TDMAAs) on a GaAs(001)-2×4 surface have been studied in the temperature range from 100 to 500 K by high-resolution electron energy loss spectroscopy (HREELS) and scanning tunneling microscopy (STM). TDMAAs is adsorbed molecularly on the surface at 100 K. Decomposition starts at about 300 K and vibration peaks of HREELS spectra due to adsorbates almost disappear between 400 and 500 K. STM images indicate that TDMAAs is adsorbed on As dimers of the GaAs(001)-2×4 surface. Only As atoms and clusters remain at the edge of the As dimer rows and nucleation of As starts at about 470 K. Decomposition of TDMAAs and As nucleation at relatively low temperature are advantageous as a source molecule in metalorganic chemical vapor deposition for nanofabrication.

Carbon nanotube (CNT) probes enhance the stability of the nano-oxidation process under dynamic-mode operation. In this paper we investigate how the hydrophobic nature of the CNT allows oxide nanostructures to be fabricated with constant aspect ratio over a wide range of relative humidity values. In particular, we characterize oxide growth by measuring both the integrated ionic current and volume expansion. Behaviour of different CNT probes was compared to assess individual stability and performance under identical voltage and humidity conditions. While much remains to be established about the relationship between exposure conditions and dynamic-mode parameters on nanoscale oxide fabrication, hydrophobicity is a key factor in the improved reliability of CNT probes over conventional ones.

Four-terminal electrical measurement is realized on a microscopic structure in air, without a lithographic process, using a home-built quadruple-scanning-probe force microscope (QSPFM). The QSPFM has four probes whose positions are individually controlled by obtaining images of a sample in the manner of atomic force microscopy (AFM), and uses the probes as contacting electrodes for electrical measurements. A specially arranged tuning fork probe (TFP) is used as a self-detection force sensor to operate each probe in a frequency modulation AFM mode, resulting in simultaneous imaging of the same microscopic feature on an insulator using the four TFPs. Four-terminal electrical measurement is then demonstrated in air by placing each probe electrode in contact with a graphene flake exfoliated on a silicon dioxide film, and the sheet resistance of the flake is measured by the van der Pauw method. The present work shows that the QSPFM has the potential to measure the intrinsic electrical properties of a wide range of microscopic materials in situ without electrode fabrication.

Local oxidation by scanning probe microscopy (SPM) is used extensively for patterning nanostructures on metallic, insulating, and semiconducting thin films and substrates. Numerous possibilities for refining the process by controlling charge density within the oxide and shaping the water meniscus formed at the junction of the probe tip and substrate have been explored by a large number of researchers under both contact mode (CM) and dynamic-force mode (DFM) conditions. This article addresses the question of whether or not the oxide growth rate and feature size obtainable by each method arise from distinctly different kinetic processes or arise simply because charge buildup and dissipation evolve over different time scales for these two cases. We report simultaneous oxide-volume and current-flow measurements for exposures performed by CM and DFM and then go on to discuss the practical realization of enhanced reliability and energy efficiency made possible by a better understanding of the relation between oxidation time and ionic diffusion using DFM.

Decomposition of cyclopentane on Ni(755) and −(111) has been investigated by temperature-programmed desorption (TPD). Adsorption of cyclopentane occurs on both surfaces by a precursor-mediated mechanism. On the (755) surface cyclopentane decomposes almost completely into adsorbed carbon and gaseous hydrogen while heating up from 123 to 573 K. On the contrary, no decomposition occurred on Ni(111). It is concluded that the active sites for the decomposition of cyclopentane are step sites. The decomposition temperature of cyclopentane is noticeably low compared with those of other saturated hydrocarbons, that is n-paraffins (C5C8) and cycloparaffins (C6C8).

With an aim of the precise control of the anodic oxidation process by atomic force microscopy, the technical improvement has been carried out based on the mechanism studies. The accuracy and reliability of the nanofabrication have been improved by the combination of ambient humidity control, improvement of instrumental performance and meniscus lifetime control. In parallel, the mechanism study has been proceeded through the detection of Faradaic current. The in situ Faradaic current detection of the nano-oxidation process can actually work as a sensitive monitor for the nano-oxidation process with a high reliability. From an engineering viewpoint with an eye to practical applications, controllable physical parameters which affect on the product size are enumerated to consider what we should do to raise the precision of nano-oxidation. Then the fast fabrication in a large area by a patchwork method, Faradaic current detection during oxidation-reduction reaction, and nanofabrication by current-control are shown as examples.

Over the past decade, multiple-scanning-probe microscope systems with independently controlled probes have been developed for nanoscale electrical measurements. We developed a quadruple-scanning-probe tunneling microscope (QSPTM) that can determine and control the probe position through scanning-probe imaging. The difficulty of operating multiple probes with submicrometer precision drastically increases with the number of probes. To solve problems such as determining the relative positions of the probes and avoiding of contact between the probes, we adopted sample-scanning methods to obtain four images simultaneously and developed an original control system for QSPTM operation with a function of automatic positional recognition. These improvements make the QSPTM a more practical and useful instrument since four images can now be reliably produced, and consequently the positioning of the four probes becomes easier owing to the reduced chance of accidental contact between the probes.

MgO/TiOx superlattices were synthesized on a MgO substrate for the combination of various thicknesses of titanium oxide layers and MgO layers by a pulsed-molecular-beam evaporation method. Wavelengths of superlattices coincided with calculated ones. The structure of titanium oxide layers and the growth mechanism of the superlattices were determined using the observation of AFM (atomic force microscopy), RHEED (reflection high-energy electron diffraction) and X-ray diffraction.

The TiC(001) surface has been observed by scanning tunneling microscopy with atomic resolution in ultrahigh vacuum. After the sample was cleaned by repeated heating at ∼1300 °C, we observed the 1×1 structure. On the other hand, the √×√ structure due to the ordered carbon vacancies formed when the sample was annealed at ∼1150 °C. We demonstrated the chemical activity of carbon vacancies of both structures for oxygen. The TiC(001)-1×1 surface with intentionally increased carbon vacancies and the TiC(001)-√×√ surface changed to a defect-free 1×1 structure with a small amount of oxygen, owing to the preferential adsorption of oxygen on the carbon vacancies.

We report on the density dependence of the morphology and electronic structure of zinc-blende-type MnAs dots using in situ photoemission spectroscopy combined with molecular-beam epitaxy. Transmission electron microscopy images showed the zinc-blende-type crystalline structure of 10-nm diameter for each dot on sulfur-passivated GaAs(001) surface. The valence-band photoemission spectra of the MnAs dots were similar to those of the diluted magnetic semiconductor ${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Mn}}_{x}\mathrm{As}$. With increasing dot density, the characteristic spectra of the zinc-blende-type MnAs persist but a weak Fermi edge appears, suggesting a metallic behavior as a result of percolation between the dots or the appearance of hexagonal MnAs as a minority phase.