The current issues of atomic oxygen (AO) effects on space materials in low earth orbit and its ground evaluation techniques are described briefly. AO is the dominant gas component at altitudes of 200-600 km. It has abundant energy to break hydrocarbon polymer bonds, thereby causing oxidation and thinning of the polymers through loss of volatile oxidation products. Therefore, ground evaluation of space materials is important. The AO source in Japan Aerospace Exploration Agency (JAXA) is based on laser breakdown phenomena. This source is one of the combined space effects test facility, which accommodates the irradiation of independent or coincidental electron beams, ultraviolet rays, and AO. Evaluation of common space materials has been done in addition to researches into new AO protective coatings and materials.
  As described herein, the AO environment, its interactions with materials, results of space experiments, ground laboratory simulation techniques, and mitigation techniques are presented.

抄録全体を表示

  Fine particles generated in plasma travel complicatedly in the plasma by various forces. Generation, transport and wall deposition of fine particles are known to cause particulate contamination problems in many situations of plasma processing. It is therefore important to clarify and evaluate the behavior of particles suspended in plasma. The most useful tool to measure particles in plasma is to detect light scattered by the particles. In this article, studies on the application of laser light scattering methods to the observation, measurement and control of fine particles in a radio-frequency plasma field are introduced.

抄録全体を表示

  The reactive plasma processing has played important roles in etching, deposition and surface modification and sustained the basis of all science and technological fields. However, the plasma processing has been developed by using external parameters of apparatus such as power, pressure and gas flow rate and so on in the industrial fields since the species, in particular, radicals in the plasma have not been able to be measured. For past 15 years, however, many diagnostics tools to measure radicals in reactive plasmas have been developed. Particularly, the measurement of radicals enabled to make a new approach for developing of plasma processing, where the plasma is precisely controlled on the basis of measured results of radicals. In this article, the radical controlled plasma and its application, where the high performances are obtained based on insights into behaviors of radicals in the reactive plasma, is described.

抄録全体を表示

  Uniformity has always been a key issue for the dry etching process. However, studies of spatial distributions of plasma in a real etcher are scarce. In this study, spatial distributions of plasma and radicals were investigated using a periscope optical sensor. The distributions of HBr/Cl₂/O₂/Ar plasma were measured in a UHF plasma gate etcher. Spatial structures of plasma were studied, and a correlation between Ar emission intensity and ion saturation current distributions was found. The results revealed a ring-shaped generation of plasma under the top shower-plate and a change in the diameter of the ring depending on the magnetic field strength or gas pressure. The transport of supplied gas and produced etchant radicals was also studied by monitoring the distributions of Cl and Cl₂⁺. Collisions with background gases diffuse the supplied gas plume and increase the dissociation of the supplied gas. This knowledge will enable tuning the etching process uniformity more easily.

抄録全体を表示

  Basic concepts, within the so-called Coulomb-blockade model, of a single-molecule transistor are reviewed. Beginning with a short summary of the experimental methods, the basic model of the electron transport theory, its single-electron-transistor limit, transport through a multi-level quantum dot (molecule), and the transport through a molecule with excited (vibrational) levels are discussed. Representative experimental results are given. Theories on the interaction between tunneling electrons and the molecular vibration are briefly described.

抄録全体を表示

  Effects, beyond the Coulomb-blockade model, of a single-molecule transistor are reviewed. The image-charge effect, elastic cotunneling effect (conduction via the Kondo effect), and the inelastic cotunneling effect [non-resonance (vibrational) inelastic electron tunneling spectroscopy] are discussed. Theories on the interaction between the Kondo effect and the molecular vibration are briefly reviewed. Inelastic Kondo effect, switching phenomena and spin-blockade effect are described. Representative experimental results are given.

抄録全体を表示

  Experimental and theoretical studies on the 2-terminal systems, which are related with a (3-terminal) single-molecule transistor, are reviewed. The measured current- bias-voltage (I-V) characteristics for the representative molecules are compared with the ab initio calculations. Molecular-vibration-induced loss of coherence and the change of the electron-transport mechanism are discussed. Mechanisms for rectification, negative differential resistance and switching of the 2-terminal systems are described. Shot-noise and thermopower studies are briefly mentioned.

抄録全体を表示

  TaAl-N thin films prepared by DC reactive sputtering with Ta and Al composite target in a gas mixture of argon and nitrogen were investigated. The electrical properties of TaAl-N thin films could be controlled by the gas flow rate rario R_N: R_N=F(N₂)/[F(N₂)+F(Ar)]. Under the condition of R_N lower than 25%, the TCR (the temperature coefficient of the resistivity) was constant at RT-300°C. The crystal structure of TaAl-N thin film was influenced by R_N.

抄録全体を表示