Principal component analysis (PCA) and multivariate curve resolution (MCR) were applied to TOF-SIMS data of a polyethylene glycol (PEG) and poly(methacrylic acid) (PMA) mixed polymer sample coexisting with Si wafer, contaminants and impurities. PCA and MCR have complementary features in regard to deciding the significant number of components and separating the pure component spectra. As a result, PCA provides useful information for elucidating the existence of characteristic components and estimating the number of components for MCR. On the other hand, MCR is useful for separating the pure component spectra and estimating the origin of each pure component. Combination of these multivariate analysis methods is expected to be applicable to TOF-SIMS data of a wide variety of samples including unknown constituents.

View full abstract

Diamond-like carbon (DLC) films are currently applied in various advanced field as magnetic disk protective layers. Mechanical endurance is difficult to maintain if a protective film is reduced to approximately 1.0 nm in thickness, which amounts to approximately several atomic layers. When considering such thin films, the corpuscular characteristics of the atomic bonding during friction and wear should be taken into account. It is difficult to maintain mechanical endurance when only several atomic layers of the protective film are involved. With the development of nanotechnology, the size of machinery is decreasing. Owing to the increasing importance of the properties of surfaces, the development of evaluation methods of the mechanical properties of DLC film surfaces is becoming indispensable. Future developments are expected as a result of current research and development. The mechanical properties of a few atomic protective layers should be evaluated. In this paper, the evaluation of the nanomechanical properties of nanometer scale surfaces is discussed and refer to our recent results on the evaluation of the nanomechanical properties of diamond-like carbon (DLC) films deposited by a bend type filtered cathodic vacuum arc (FCVA) and electron cyclotron resonance chemical vapour deposition (ECR-CVD) methods, nanoperiod multilayer films composed of DLC and other materials deposited by radio frequency (RF) sputtering, and a lubricant on DLC protective films. In the field of micro-nano technology, nanoscale evaluation technology is important for determining surface mechanical properties. The evaluation of thin-film surfaces has been performed by nanoindentation tests and nanoscratch tests using an atomic force microscopy. On the other hand, nanowear tests can evaluate the average mechanical properties of a thin-film, it has become possible to evaluate a difference of about 0.1 nm by choosing appropriate loads. The properties of vibrational wear, surface friction, viscoelastic properties and other dynamic properties can be evaluated by applying a force modulation method using scanning probe microscope (SPM). Moreover, it is effective to evaluate mechanical properties of surfaces. Surface friction durability has been studied by measuring the friction force and current distribution in vibration tests.

View full abstract

In this review, the principle of EELS is described, which is one of the most effective techniques to evaluate bonding states of carbon. Evaluation of DLC film using Reflective EELS is also given details.

View full abstract

Diamondlike carbon (DLC) is an amorphous carbonaceous allotrope, which is composed of sp² carbon, sp³ carbon, and hydrogen. This paper reviews the authors' analysis of the surface chemical structure of DLC films by x-ray photoelectron spectroscopy (XPS). The C 1s spectra of the DLC films were analyzed by the Doniach-Šunjic function convoluted with a Gaussian function and were decomposed into four components, which take account of the differences between sp² and sp³ carbons and between carbon-carbon and carbon-hydrogen bonds. This analysis agrees with actual hydrogen distribution analyzed by high-resolution elastic recoil detection (ERD). On the other hand, a modified gas-phase chemical derivatization (GCD) method with the help of a simple mathematical treatment is also reviewed in order to analyze oxygen-related surface functional groups on DLC surfaces. The method takes account of the side reactions which complicate the analysis and has well explained the oxidation process of the DLC surface. These discussions conclude that XPS would be a comprehensive analytical tool for the DLC surface.

View full abstract