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We studied a surface modification technique for indium tin oxide (ITO) anodes without precleaning and resist banks for manufacturing organic light-emitting diodes (OLEDs) by inkjet printing. The ITO surface modified by inductively coupled plasma (ICP) with an optimized CF4/O2 (7:3) gas mixture improved both its hydrophilicity and its work function, while the resist surface treated by the plasma became hydrophobic. The resist and ITO surfaces treated by plasmas of various gas mixtures (i.e., CF4, CF4/Ar (1:2), CF4/O2 (x:1; x=1, 7/3, 4, and 9) were analyzed by X-ray photoelectron spectroscopy (XPS) of the C 1s, F 1s, O 1s, and In 3d5/2 core levels. On the uncleaned ITO surfaces modified by CF4/O2 plasmas, organic contaminants were removed more efficiently and the deposition of CFx on the remaining contaminants decreased with increasing oxygen. The amount of F in the form of InFx increased using the CF4/O2 (7:3) plasma in comparison with that using the CF4/Ar and CF4 plasmas. We investigated the effect of adding oxygen to CF4 on the change in gaseous species produced in the plasma chamber by mass spectrometry. In the CF4/O2 (7:3) plasma, the peak intensities of F+, HF+, F2+, O+, and O2+ were higher than those in the CF4 plasma. The results suggest that In2O3 was generated by the oxidation of indium with O, and InFx was generated by the fluoridation of indium with HF. By introducing InFx onto ITO surfaces using the CF4/O2 plasma, the hole-injection energy barrier could be reduced.

"Atomic force microscopy (AFM) compression simulation" approach together with "CASSCF/AM1 ONIOM" model calculation method is used for investigating the quenching mechanism of the luminescence in green fluorescent protein (GFP). Our results show that the electronic properties and steric conformations of the chromophore's neighboring residues strongly influence the photo decay behaviors in GFP.

Antisticking layers (ASLs) on UV nanoimprint lithography (UV-NIL) molds were characterized by scanning probe microscopies (SPMs) in addition to macroscopic analyses of work of adhesion and separation force. Local physical properties of the ASLs were measured by atomic force microscopy (AFM) and friction force microscopy (FFM). The behavior of local adhesive forces measured with AFM on several surfaces was consistent with that of work of adhesion obtained from contact angle. The ASLs were coated by two different processes, i.e., one is a vapor-phase process and the other a spin-coating process. The homogeneity of the ASLs prepared by the vapor-phase process was better than that of those prepared by the spin-coating process. In addition, we measured the thicknesses of ASL patterns prepared by a lift-off method to investigate the effect of the ASL thicknesses on critical dimensions of the molds with ASLs and found that this effect is not negligible.

Most problems in photomask fabrication such as pattern collapse, haze, and cleaning damage are related to the behavior of surfaces and interfaces of resists, opaque layers, and quartz substrates. Therefore, it is important to control the corresponding surface and interface energies in photomask fabrication processes. In particular, adhesion analysis in microscopic regions is strongly desirable to optimize material and process designs in photomask fabrication. We applied the direct peeling (DP) method with a scanning probe microscope (SPM) tip and measured the adhesion of resist patterns on Cr and quartz surfaces for photomask process optimization. We also studied the effect of tip shape on the reproducibility of adhesion measurements and the dependence of collapse behavior on the resist profile. We measured lateral forces between the resulting collapsed resist pillar and the Cr or the quartz surface before and after the sliding and related these observed lateral forces to the static and kinetic frictional forces, respectively. We also studied the effect of surface modification of the Cr and quartz surfaces with silanization reagents on adhesion measured with the DP method. Resist adhesion could be controlled by surface modification using silanes. We also discuss the relationship between the adhesion observed with the DP method and the properties of the modified surfaces including water contact angles and local adhesive forces measured from force–distance curves with an SPM.

A film with a superhydrophobic rough surface was prepared on an AT-cut quartz crystal resonator (QCR). Using the QCR with the film, we measured energy dissipation at the ultrasonically oscillating superhydrophobic surface in various liquids such as water, ethanol and water–glycerol mixtures. The QCR was successfully used to determine the mode of contact of the rough surface with each liquid, i.e., either Wenzel or Cassie contact. Furthermore, it was found that the interfacial friction strongly depended on the contact mode. The interfacial friction was reduced by ca. 50% when the contact mode was the Cassie type.

We demonstrate here the observation of the interaction between DNA and silanized cover glass surfaces using a fluorescence microscope and an atomic force microscope (AFM). Two-component surface modification with one alkylsilane mixed with another silane derivative containing amino end groups enhanced the adsorption of negatively charged DNA molecules due to the electrostatic interaction with positive charges of protonated amino end groups. We investigated the electrostatic interaction of the DNA molecules with the mixed silanized surfaces as a function of the concentration of the amino end groups. In addition, interaction on molecular scales was demonstrated by a newly developed double combing method.

The effects of chain length on adhesive force between a gold-coated tip and a Au(111) substrate covered with alkanethiol self-assembled monolayers (SAMs) were studied. By microcontact printing (µ-CP), we prepared a patterned surface covered with two types of n-alkanethiol that have the same CH3-terminal functional group but different chain lengths. As a method for mapping adhesive force, pulsed-force-mode atomic force microscopy (PFM-AFM) was used. PFM-AFM enables the simultaneous imaging of surface topography and adhesive force. Regardless the use of the same CH3-terminal functional group to modify a surface, a difference in adhesive force corresponding to the printed pattern was observed. The adhesive force on a printed region covered with a longer alkanethiol SAM was slightly smaller than that of an unprinted region covered with a shorter alkanethiol SAM chemisorbed from solution after µ-CP. The possible molecular mechanisms for the difference in the observed adhesive force were discussed in detail.

A molecular dynamics (MD) method is used to simulate the molecular stick-slip motion and the friction anisotropy observed experimentally between an atomic force microscope (AFM) tip and an ordered monolayer of n-alkane chains which tilt in one of six equivalent stable directions. A slider with a single atomic scale protrusion, connected to an external force control unit via three orthogonal springs, is used to model the AFM tip apex with cantilever springs under feedback regulation of the applied normal force. Although there is almost no interfacial commensurability between the tip atomic lattice and the sample molecular lattice, molecular lattice-resolved images are observed due to molecular scale stick-slip motion when the size of the protrusion is comparable to the molecular lattice constant. The present MD simulation can provide an explanation of why we can see a molecular lattice in contact AFM.

Current information technologies use semiconductor devices and magnetic/optical discs, however, it is foreseen that they will all face fundamental limitations within a decade. This paper reviews the prospects and problems of single molecule devices, including switching devices, wires, nanotubes, optical devices, storage devices and sensing devices for future information technologies and other advanced applications in the next paradigm. The operation principles of these devices are based on the phenomena occurring within a single molecule, such as single electron transfer, direct electron-hole recombination, magnetic/charge storage and regand-receptor reaction. Four possible milestones for realizing the Peta (1015)-floating operations per second (P-FLOPS) personal molecular supercomputer are described, and the necessary technologies are listed. These include, (1) two terminal conductance measurement on single molecule, (2) demonstration of two terminal molecular device characteristics, (3) verification of three terminal molecular device characteristics and (4) integration of the functions of “molecular super chip”. Thus, 1000 times higher performance information technologies would be realized with molecular devices.

The effects of new insulating materials of lithium fluoride and lithium carboxylates at an aluminum cathodic interface on the performance of organic electroluminescent (EL) devices are described. Three different cathode interface materials are used: lithium salts of fluoride, acetate, and benzoate. We compare the current density–voltage (I–V) and the luminance–voltage (L–V) characteristics of the devices with Al/lithium carboxylates with those of the devices with Al/LiF or an Al cathode. We find that the bilayer cathodes with lithium carboxylates exhibit better device performance than the cathodes with LiF or the Al cathode itselt. In particular, the device with lithium benzoate gives the best performance of all the devices studied. The improvements are attributed to the lowering in work function of the cathode due to lithium metal formation by the higher reactivity of lithium carboxylates than LiF, with hot Al atoms impinging on these insulating materials.

Molecular dynamics and simple phenomenological simulations are used to model the friction between two ordered monolayers of alkyl chains bound at their ends, i.e., pinned atoms, to rigid substrates. We could previously interpret the origin of friction differences in organic monolayer systems by comparing these two simulations. In the present work, insight given by such comparisons is described in detail. In particular, the molecular mechanism of energy dissipation, the origin of friction force microscopic image, the chain length dependence, the packing density (tilt angle) dependence, and anisotropy of friction due to sliding direction are discussed by taking into account the effects of the molecular properties on two simplified potentials of the monolayer films. One potential is due to the lateral collective deformation of a film, and the other is a corrugated interfacial potential between films facing each other. This interpretation of molecular lubrication mechanisms in terms of the chemical and physical properties of molecules using the simple phenomenological model can be extended widely to understand the bases of chemical force microscopy by friction force microscopy.

Molecular dynamics and corresponding simple phenomenological simulations are used to interpret the difference in wearless friction observed between two ordered monolayers with CH3 and CF3 terminal groups of the same alkyl chains bound at their ends to rigid substrates. The simulated interfaces correspond well to mesoscopic sliding interfaces. The simplified model previously proposed by us, where the frictional properties at such sliding interfaces are governed by two potentials which are closely related to the chemical and the structure of the film, suggests that the above frictional difference can be qualitatively interpreted by the difference in slopes of the corrugated interfacial potentials between two films at the repulsive regions.

Molecular dynamics and simple phenomenological simulations are used to model the friction between two ordered monolayers of alkane chains bound at their ends to rigid substrates. Results of calculations using these methods suggest that the frictional properties at a sliding interface between the ordered films are governed by two simplified potentials. One is a potential due to the lateral collective deformation of a film and the other is a corrugated interfacial potential between films facing each other. These two potentials are closely related to the nature of the films, i.e., their physical and chemical properties. In addition, the simplified models can be greatly extended to clarify the frictional behavior of other weakly interacting interfaces such as hydrogen-terminated diamond surfaces.

A self sensitive probe was composed of a piezoelectric tuning fork and a bent optical fiber tip for scanning near-field optical/atomic force microscopy. The topography, optical image and fluorescent spectrograph were successfully derived using the combined probe. The probe showed 1.1 nm vertical resolution at the tip-sample distance regulation. The combined probe showed single or twin resonant frequency peaks while the original tuning fork has only one resonant frequency of 32.7 kHz. In the twin peaks-case, results for various combination patterns suggested that one of the peaks is the response for a free arm of the tuning fork and the other is the response for the combined arm. The near-field acoustic effect was detected in the tuning fork probe as a small effect, but the effect was not detected in the combined probe.

Heat-induced phase separation of fluorocarbon-hydrocarbon self-assembled monolayers (SAMs) on a Au(111) surface was studied by scanning tunneling microscopy (STM), atomic force microscopy (AFM) and friction force microscopy (FFM). Phase-separated domains were depressed by 0.3 nm with a lateral dimension of 20–200 nm. The friction forces on the higher parts were smaller than those on the lower domains. The higher parts were assigned to the hydrocarbon chains, because the fluorocarbon chains should have a larger friction force acting on them than the hydrocarbon chains against the silicon nitride tip. Phase separation suggests cleavaging of the S–S bonds of disulfides in the SAMs. XPS measurements clearly showed an increase in the isolated Au–S binding species, suggesting the existence of the thiolate (monomer).

The mechanical properties of a Langmuir-Blodgett (LB) film in water were investigated using an atomic force microscope with lateral force modulation. During the force curve measurement, the dynamic friction force is measured by observing the amplitude and phase of the cantilever torsion vibration, as the sample is deformed by a tip with gradually increasing normal force. In contrast to conventional friction force microscopy, the friction measurement is performed without x–y scanning, and therefore is in real time. This method was applied to a LB film consisting of an arachidic acid (AA) single layer on top of a single layer of partially fluorinated ether of carboxylic acid (PFECA), and interesting results were obtained. In particular, the film was found to be stable for a short period (

A scanning near-field optic/atomic force microscope (SNOAM) was improved using a novel optical fiber probe. The optical fiber probe has a mirror grounded on the ridge for the optical lever of AFM. The resonant characteristics of the optical fiber probe were adequate for a noncontact AFM cantilever: the typical Q factor and resonant frequency were 574 and 10.9 kHz, respectively. The topographical and optical resolution of the SNOAM was better than 100 nm for a standard sample of chromium patterns on a quartz substrate. The SNOAM successfully provided topographies and optical images of optical fiber ends simultaneously. These images indicated that the optical pattern of the core was markedly influenced by the surface roughness of the optical fiber end.