Seizo Morita

Osaka University | Handai · The Institute of Scientific and Industrial Research (ISIR)

We demonstrate a method to substitute individual adsorbate atoms into a Si(111)-(7 × 7) substrate using the tip of an atomic force microscope (AFM) at room temperature. We show that single Sn atoms diffusing within the half-unit-cells (HUCs) of the Si(111)-(7 × 7) substrate can be substituted into Si adatom sites via a close approach of the tip, wh...

We investigated the role of lateral force components on the lateral manipulation of intrinsic Si adatoms toward a vacancy site on a Si(111)-(7×7) surface using noncontact atomic force microscopy at room temperature. Lateral atom manipulation was accomplished via constant-height scans using a set of tips with varying chemical reactivities. We determ...

Noble metal nanostructures dispersed on metal oxide surfaces have applications in diverse areas such as catalysis, chemical sensing, and energy harvesting. Their reactivity, chemical selectivity, stability, and light absorption properties are controlled by the interactions at the metal/oxide interface. Single-atom metal adsorbates on the rutile TiO...

We assemble bi-stable silicon quantum dots consisting of four buckled atoms (Si4-QD) using atom manipulation. We demonstrate two competing atom switching mechanisms, downward switching induced by tunneling current of scanning tunneling microscopy (STM) and opposite upward switching induced by atomic force of atomic force microscopy (AFM). Simultane...

Supported nanoclusters have attracted considerable attention in recent years, by virtue mainly of their unique size-dependent properties. Various novel approaches have been developed to create nano-clusters with different functionalities on surfaces. In this study, we propose an alternative approach to the assembly of various nano-clusters atom-by-...

In the atom manipulation process with atomic force microscopy (AFM) at room temperature, reduction of the local energy barrier induced by interaction forces between atoms of a tip and a surface plays a key role. Thismeans that the force value depending on the tip-apex condition determines the success of manipulation. In the first part of this chapt...

Single-atom/molecule manipulation for fabricating an atomic-scale switching device is a promising technology for nanoelectronics. So far, scanning probe microscopy studies have demonstrated several atomic-scale switches, mostly in cryogenic environments. Although a high-performance switch at room temperature is essential for practical applications,...

We have studied the local properties of single Pt atoms adsorbed on hydroxylated TiO2(110 ) -(1 ×1 ) by combining noncontact atomic force microscopy (nc-AFM) and first-principles calculations. Room-temperature high-resolution nc-AFM images for the most frequently observed contrast modes reveal bright and elongated protrusions that can be traced bac...

Atomic force microscopy (AFM) has demonstrated its capabilities as a nanotechnology tool. These capabilities include imaging/characterizing individual atoms on various surfaces and manipulating atoms and molecules. Here, we report how atom manipulation works on a well-known semiconducting surface, Si(111)-(7 × 7) . To quantify the stochastic behavi...

Since the publication of Noncontact Atomic Force Microscopy Vol. 2 in 2009, the noncontact atomic force microscope (NC-AFM), which can image even insulators with atomic resolution, has achieved remarkable technical progress especially on (a) Tip Modification , (b) Control of Atomic Force , and (c) qPlus Sensor /Quartz Tuning Fork. This third volume...

Nanoclusters supported on substrates are of great importance in physics and chemistry as well as in technical applications, such as single-electron transistors and nanocatalysts. The properties of nanoclusters differ significantly from those of either the constituent atoms or the bulk solid, and are highly sensitive to size and chemical composition...

Atomic force microscopy (AFM) can now not only image individual atoms but also construct atom letters using atom manipulation method even at room temperature (RT). Therefore, the AFM is the second generation atomic tool following the scanning tunneling microscopy (STM). However the AFM can image even insulating atoms, and also directly measure/ma...

Quantum degeneracy is an important concept in quantum mechanics with large implications to many processes in condensed matter. Here, we show the consequences of electron energy level degeneracy on the conductance and the chemical force between two bodies at the atomic scale. We propose a novel way in which a scanning probe microscope can detect the...

Atomic force microscopy (AFM) with atomic resolution has opened up a new “atom world” based on the chemical nanoscale force. In the noncontact regime where a weak attractive chemical force appears, AFM has successfully achieved atomically resolved imaging of various surfaces. In the near-contact regime, where a strong attractive chemical force or P...

The effect of tip chemical reactivity on the lateral manipulation of intrinsic Si adatoms toward a vacancy site on a Si(111)-(7×7) surface has been investigated by noncontact atomic force microscopy at room temperature. Here we measure the atom-hopping probabilities associated with different manipulation processes as a function of the tip-surface d...

We report force mapping experiments on Si(111)-(7×7) surfaces with adsorbed hydrogen, using atomic force microscopy at room temperature supported by density functional theory (DFT) simulations. On the basis of noncontact atomic force microscopy (NC-AFM) images as well as force versus distance curves measured over both hydrogen-passivated and bare S...

The Ag:Si(111)-(root 3 x root 3)R30 degrees surface structure has attracted considerable debate concerning interpretation of scanning tunneling microscope (STM) and noncontact atomic force microscope (NC-AFM) images. In particular, the accepted interpretation of atomic resolution images in NC-AFM has been questioned by theoretical and STM studies....

We investigate thin insulating CaF2 films on a Si (111) surface using a combination of noncontact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM). Atomic-scale NC-AFM and KPFM images are obtained in different imaging modes by employing two different tip polarities. The KPFM image contrast and the distance-dependent variati...

Site-specific force measurements on a rutile TiO2(110) surface are combined with first-principles calculations in order to clarify the origin of the force contrast and to characterize the tip structures responsible for the two most common imaging modes. Our force data, collected over a broad range of distances, are only consistent with a tip apex c...

We simultaneously measured the force and tunneling current in three-dimensional (3D) space on the Si(111)-(7 × 7) surface using scanning force/tunneling microscopy at room temperature. The observables, the frequency shift and the time-averaged tunneling current were converted to the physical quantities of interest, i.e. the interaction force and th...

Water molecules adsorbed on the CeO(2)(111) surface are investigated by non-contact atomic force microscopy (NC-AFM) at several tip-sample temperatures ranging between 10 and 300 K. Depending on the strength of the tip-surface interaction, they appear as triangular protrusions extended over three surface oxygen atoms or as small pits at hollow site...

This special issue is focussed on high resolution non-contact atomic force microscopy (AFM). Non-contact atomic force microscopy was established approximately 15 years ago as a tool to image conducting and insulating surfaces with atomic resolution. Since 1998, an annual international conference has taken place, and although the proceedings of thes...

Simultaneous scanning force/tunneling microscopy measurements are carried out on the Si(111)-(7× 7) surface using quartz cantilevers. The retrace scanning mode enables constant height imaging even under heavy drift conditions at room temperature. Relatively clean tungsten tips produce huge time-averaged tunneling currents (< It>) in the chemical bo...

We present a combined non-contact atomic force microscopy and Kelvin probe force microscopy (KPFM) investigation of the structural and electrical properties of Au nanoclusters on a TiO2 model-oxide surface at room temperature. The KPFM images reveal an increase in the local contact potential difference (LCPD) of Au clusters with respect to the supp...

Scanning tunneling microscopy (STM) has opened up the new nanoworlds of scanning probe microscopy. STM is the first-generation atomic tool that can image, evaluate and manipulate individual atoms and consequently can create nanostructures by true bottom-up methods based on atom-by-atom manipulation. Atomic force microscopy is a second-generation at...

We report on the adsorption and manipulation of K atoms on a hydroxylated TiO2(110)-1×1 surface using low-temperature noncontact atomic force microscopy. At low coverage, first-principles GGA + U calculations reveal favorable adsorption sites that are consistent with the experimentally observed adsorption positions on the upper-threefold hollow sit...

We studied about a method of fabricating quartz cantilevers with a conductive tip. The quartz cantilever is a key part for small-amplitude dynamic force microscopy combined with an optical deflection sensor. The stiffness of cantilevers enables us a stable small-amplitude operation, because a sufficiently high oscillation energy, which is based on...

We studied about a method of fabricating quartz cantilevers with a conductive tip. The quartz cantilever is a key part for small-amplitude dynamic force microscopy combined with an optical deflection sensor. The stiffness of cantilevers enables us a stable small-amplitude operation, because a sufficiently high oscillation energy, which is based on...

A single atomic defect on an ionic crystal surface was manipulated at the atomic level using an atomic force microscope. During raster scanning, the defect was manipulated at near the tip--sample distance and at room temperature. The defect, which is imaged as a sharp half-moon shape, moves continuously if the tip is close to the sample surface. Th...

The constant vibration mode and the constant excitation mode in noncontact atomic force microscopy were compared to investigate the force interaction between tip and surface. As a result, we found that the constant excitation mode is much more gentle than the constant vibration mode. We also succeeded in atomic resolution imaging on InP(110) surfac...

A single atomic defect on an ionic crystal surface was manipulated at the atomic level using an atomic force microscope. During raster scanning, the defect was manipulated at near the tip–sample distance and at room temperature. The defect, which is imaged as a sharp half-moon shape, moves continuously if the tip is close to the sample surface. The...

It is generally difficult to obtain subsurface information by scanning probe microscopy. For certain tip conditions, we observe subsurface back-bond atoms on the Si( 111)-(7x7) surface by atomic force microscopy without removing Si adatoms. We propose an imaging mechanism that is based on the interaction of the adatom with the back-bond atoms. Our...

We propose dynamic force microscopy (DFM) that employs a quartz cantilever in combination with an interferometric deflection sensor. The high stiffness of the quartz cantilever allows DFM to be performed at oscillation amplitudes as small as 1 Å. DFM topographic images can be obtained for a Si(111)-(7 × 7) surface even when a blunt tip is used at r...

We simultaneously obtain spatial maps of the interaction force and current between conductive tips and the Si(111)-(7×7) surface. The difference in the topographic profiles between atomic force microscopy and scanning tunneling microscopy is clearly visualized. We observe a current drop in the region where the chemical bonding force between the tip...

We perform simultaneous atomic force microscopy (AFM) and scanning tunneling microscopy (STM) measurements on the Si(111)-(7×7) surface. AFM/STM constant height images are obtained at various tip-surface distances. Force/current distance spectroscopy using the same tip apex allows us to estimate the relative tip-surface distance for each image as...

In this article, the authors present the simultaneous noncontact atomic force microscopy and scanning tunneling microscopy measurement of the Ge (111)-c (2×8) surface using PtIr-coated Si cantilevers at room temperature. In both frequency shift and time-averaged tunneling current images at constant-height mode, each atom was clearly resolved. The i...

In order to determine the molecular structure by x-ray diffraction analysis, it is very important to grow high quality protein crystals. The molecular resolution imaging of soluble protein crystals such as the tetragonal lysozyme (110) face in saturated solution is demonstrated using frequency-modulation atomic force microscopy (FM-AFM). The surfac...

The TiO(2)(110)-(1 x 1) surface is investigated using non-contact atomic force microscopy (nc-AFM) at 80 K. We successfully obtained a distinct type of image contrast mode which does not exhibit hydroxyl (OH) impurity defects that mostly appear in common nc-AFM images. We named the obtained distinct type of image contrast as the 'hidden mode'. The...

Scanning probe microscopy (SPM) methods such as scanning tunneling microscopy (STM) and noncontact atomic force microscopy (NC-AFM) are the basic technologies for nanotechnology and also for future bottom-up processes. In Sect.23.1, the principles of AFM such as its operating modes and the NC-AFM frequency-modulation method are fully explained. The...

Noncontact atomic force microscopy (NC-AFM) achieved not only single atom imaging, but also the single-atom chemical identification by the force spectroscopy and the force mapping. Moreover, by the precise tip-sample distance control around the nearcontact region, AFM achieved not only the conventional vertical and lateral atom manipulation of sing...

During the past 20 years, the manipulation of atoms and molecules at surfaces has allowed the construction and characterization of model systems that could, potentially, act as building blocks for future nanoscale devices. The majority of these experiments were performed with scanning tunnelling microscopy at cryogenic temperatures. Recently, it ha...

We present dynamic force-microscopy experiments and first-principles simulations that contribute to clarify the origin of atomic-scale contrast in Kelvin-probe force-microscopy (KPFM) images of semiconductor surfaces. By combining KPFM and bias-spectroscopy imaging with force and bias-distance spectroscopy, we show a significant drop of the local c...

We have performed simultaneous scanning tunneling microscopy and atomic force microscopy measurements in the dynamic mode using metal-coated Si cantilevers at room temperature. Frequency shift (Δf) and time-average tunneling current (〈It〉) images are obtained by tip scanning on the Si(111)-(7×7) surface at constant height mode. By measuring site-sp...

Imaging of surface atoms with simultaneous measurement of noncontact atomic force microscopy (NC-AFM) and scanning tunneling microscopy (STM) is performed. Si cantilever coated with PtIr provides stable AFM/STM operations to obtain high spatial resolution images. AFM/STM measurements on Si(111)-(7x7), Ge(111)-c(2x8), and TiO2(110) surfaces are pres...

We present, using frequency modulation atomic force microscopy, two methods for rapid atom discrimination. Both methods visualize chemical difference on difference atom sites. Signals corresponding to absolute minimum values of the obtainable frequency shift are used. In the first method, two-dimensional force mapping, quantitative force analysis f...

We perform vacancy-mediated lateral manipulations of Si adatoms on the Si(111)-(7×7) surface by atomic force microscopy at room temperature. A variety of line profiles associated with different atom hopping processes is observed in successive topographic line scans for the atom manipulations. Atom manipulation statistics show stochastic behavior in...

The ability to incorporate individual atoms in a surface following predetermined arrangements may bring future atom-based technological enterprises closer to reality. Here, we report the assembling of complex atomic patterns at room temperature by the vertical interchange of atoms between the tip apex of an atomic force microscope and a semiconduct...

The distance between bright spot in a dimer on the Si(100)-(2×1) surface imaged by noncontact atomic force microscopy (NC-AFM) is analyzed. We used in the analysis only high-spatial-resolution topographic NC-AFM images obtained using different tips at room temperature. Atoms in the dimer was clearly resolved, which enabled us to analyze the distanc...

The topographic image of dynamic force microscopy (DFM) keeping the frequency shift (Δfz) constant at tiny cantilever oscillation amplitudes corresponds to the constant-vertical force (Fz) gradient surface, while the interpretation becomes complicated at larger oscillation amplitudes. We discuss how Fz and the potential energy (U) act on the tip du...

An instrument that combines the strengths of AFM and STM allows determination of the forces required to move a single atom on a surface.

The effect of heat treatment during evaporation of C60 on the characteristics of a photovoltaic cell with a structure of indium-tin-oxide (ITO)/C60/poly(3-hexylthiophene) (PAT6)/Au was studied. The C60 films were fabricated on the substrates at different temperatures and the C60/PAT6 heterojunction of this photovoltaic cell was fabricated by spin-c...

Recent activities of the eight divisions (Applied Surface Science, Electronic Materials & Processing, Nanometer Structures, Plasma Science & Technique, Surface Engineering, Surface Science, Thin Film, and Vacuum Science and Technology) of the International Union for Vacuum Science, Technique and Applications (IUVSTA) are reported.

Using noncontact atomic force microscopy (NC-AFM), we analyzed the height distribution of individual atoms by atomically resolved topography of Pb/Si(111)-(√3 × √3) mosaic phase surfaces, discriminated Pb, and substituted Si adatoms atom-by-atom. This successfully revealed the atom-by-atom chemical coordination effect in the height distribution of...

Using room-temperature (RT) site-specific force spectroscopy F(Z), we developed a nondestructive single-atom chemical identification method at RT, which is independent of tip, topography (height difference) and chemical coordination, but dependent on atom species, with atomic resolution. We demonstrated atom-by-atom chemical identification of inter...

An atomic force microscope (AFM) under noncontact and nearcontact regions operated at room-temperature (RT) in ultrahigh vacuum, is used as a tool for topography-based atomic discrimination and atomic-interchange manipulations of two intermixed atomic species on semiconductor surfaces. Noncontact AFM topography based site-specific force curves prov...

Most high-resolution scanning tunnelling microscopy studies on insulating films thus far have been restricted to samples of less than one monolayer thickness on conducting substrates. On the other hand, insulating films with more than one monolayer are crucial to electrically decouple the conducting substrate. In such a case, atomic force microscop...

Surface and subsurface oxygen vacancies on the slightly reduced CeO(2)(111) surface have been studied by atomic resolution dynamic force microscopy at 80 K. Both types of defect are clearly identified by the comparison of the observed topographic features with the corresponding structures predicted from recent first-principles calculations. By comb...

By means of force spectroscopy measurements performed with the cantilever first and second flexural modes under the frequency modulation detection method, the authors corroborate the validity of the relation between tip-surface interaction force and frequency shift for force spectroscopy acquisition using higher cantilever eigenmodes. They estimate...

We perform the local structure change on Pb/Ge(111) by frequency modulation atomic force microscopy (FM-AFM). The positions of the Pb and Ge adatoms embedded in the plane of the Pb/Ge(111)-c(2 × 8) surface system are interchanged using the AFM tip. We collect the Pb adatoms into a local area to induce the local structure change to a (2 × 2) periodi...

The authors have performed distortionless atom imaging and force mapping experiments, under a large thermal drift condition at room temperature (RT), using frequency modulation atomic force microscopy (FM-AFM) that had been done previously only at low temperature. In the authors’ experimental scheme, three-dimensional position feedback with atom tr...

Vacancy-mediated lateral manipulations of intrinsic adatoms of the Si(111)-(7x7) surface at room temperature are reported. The topographic signal during the manipulation combined with force spectroscopy measurements reveals that these manipulations can be ascribed to the so-called pulling mode, and that the Si adatoms were manipulated in the attrac...

Scanning probe microscopy is a versatile and powerful method that uses sharp tips to image, measure and manipulate matter at surfaces with atomic resolution. At cryogenic temperatures, scanning probe microscopy can even provide electron tunnelling spectra that serve as fingerprints of the vibrational properties of adsorbed molecules and of the elec...

The iron silicide c(4 × 8) surface is expected to be a precursor surface in optoelectronic and magnetic technological fields because of its probability of realizing thin, flat and well-ordered film on the silicon surface. The structure of the c(4 × 8) film, however, has not been determined in spite of scanning tunnelling microscopy experiments and...