Surface segregation or the formation of high order structure in surface layer for polymer alloys was clarified by NRA, XPS or Dynamic SIMS. Several concrete examples of surface analysis for such polymer alloys were shown and discussed.
The aim of this study is to detect small amounts of impurities and defects affecting metal-oxide-semiconductor (MOS) device characteristics in SiO2/Si samples, which is necessary for making electron spectroscopy for chemical analysis (ESCA) useful for device application. The process is not easy because X-ray-induced charging makes it difficult to determine chemical states accurately and also because the amount of impurities and defects is usually below the ESCA detection limit. We have found ways to make the above detection possible in the course of studying the effects of charging on our samples. Namely, the above aim can be accomplished by measuring electron kinetic energy changes (equivalent to surface potential changes) or sample (sample-to-ground) current changes during X-ray irradiation to detect charges caused by impurities or defects.
Over the years, organic molecular crystals including metal-phthalocyanines or C60 have attracted much attention as source materials for the next generation high-density optoelectronic devices. To fabricate such devices, formation of desired nanostructures is required. But it is difficult to apply conventional photolithography techniques to create the nanostructures of such organic materials. As the method to fabricate a nanostructure of an organic material, we payed much attention to a selective growth technique, which utilizes differences in the sticking coefficients of an organic material on various substrates. Here, we report the results of the selective growth of organic molecules on alkali halides and layered materials as the substrates. We also discuss a novel method to fabricate the organic molecule nanostructure, which takes advantage of a combination of the selective growth and scanning probe microscope lithography techniques.
Tougaard's formula gives the relation between the XPS inelastic background and the energy-loss probability of a photoelectron in solids. Therefore, it is necessary to know one of these in order to calculate the other. Very recently, it turned out that an optimization technique can reasonably and simultaneously estimate both the probability and the background of an unknown material. The method is based on two very general assumptions and a powerful non-linear optimization algorithm. Once the background is calculated, it is possible to discuss the shape of the loss function, the shape of the photoelectron peak, the Auger electron peak intensity and its shape, etc., which had all been very difficult to evaluate. In this report, the method's principle and main results obtained so far are discussed.
A tunneling-electron luminescence (TL) microscope using the tip collection method has been developed for realspace characterization of the electronic and optical properties of materials and structures with nanometer-level spatial resolutions. Tip collection can provide spatial resolution, luminescence collection yield, and thermal isolation. The new microscope has a novel conductive transparent tip that injects tunneling electrons into a sample and simultaneously collects tunneling-electron luminescence. Using the TL microscope, high S/N TL spectra and TL images with high spatial resolution (<3 nm) were successfully obtained on the cross-section of GaAs/AlAs multiple quantum wells at low temperatures.
We discuss the n electronic states of a graphite sheet which has topological defects or edges on a nanometer scale. The former is the case that pairs of pentagonal and heptagonal rings are introduced in the hexagonal network of a graphite sheet. In the latter case, we take notice of nanographite, which is a kind of graphite fragment of a nanometer size. Through the whole, we demonstrate how the π electronic states vary under the control of the nanometer topology of the three-coordinated π-electron network in a graphite sheet.
In-Situ observation of Ice growth was successfully performed using an Atomic Force Microscope (AFM). The dynamic phenomena of ice growth was investigated directly by introducing water vapor into the chamber under controlled temperature and atmosphere.
A stepped Si(111) surface consisted of atomically flat terraces and step bands where atomic steps bunched was prepared by direct-current heating in UHV. An electron-emission spectrum, generated with a field-emission-type electron gun, was observed in situ with a scanning Auger microscope (SAM). The electron-emission spectrum obtained in the direct mode included only characteristic Auger electron (AE) peaks of silicon and a secondary-electron (SE) peak. The AE/SE spectrum obtained from the atomically flat Si(111) terrace between the steps was different from the spectra from sputtered clean silicon (111) and (100) surfaces as to the background shape and the relative intensities of the characteristic peaks. We also found that the stepped surface morphology could be imaged by using only the energy-analyzed SEs when the intensity was defined as the difference between the peak height and the background intensity.