It has been demonstrated by previous studies that the chemisorption of molecules or atoms onto a solid surface can alter its intrinsic stress. Now this process has been turned on its head, with the chemical reactivity of the surface being altered by external stress. We report herein how the dissociation reactions of O₂ on Cu(001), O covered Cu(001), and Si(001) surfaces are influenced by the stress. In each case the activation barriers for direct dissociation and/or for trapping precursor-mediated dissociation and the depth of trapping well are sensitively altered by the externally applied tensile stress. These results revealed that stress could significantly altered surface reactivity, and that the stress has the potential to control the surface reactions as well as the dynamics.

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  We have studied the electronic structure of the partially N-adsorbed Cu(100) surface, where a lattice contraction is spontaneously induced on the clean Cu region. As a result, an increase of the d-band width due to the lattice constant reduction on the clean Cu region was experimentally confirmed. The shift of the sp-state above the Fermi level was also observed. The experimental facts were well reproduced by first-principles calculations for the strained Cu(100) surface. An interpretation of the strain-induced change on the surface electronic structure in terms of tight-binding model, suggested here, will be useful to discuss the surface chemical reaction change due to the lattice strain.

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  To study the relation between the strain and the electronic structure in two-dimensional (2D) nanoislands of Si and Ge on the Si(111)-7×7 surface, we made the nanoislands the same size and measured with the angle resolved ultraviolet photoelectron spectroscopy (ARUPS), the scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS). We also calculated the relation based on the density-functional theory. In the calculation, the dangling-bond state at the strained adatom on the nanoisland (S^R state) shifts to lower energy, which has a liner dependence with the height of the adatoms. The ARUPS spectrum and the STS show characteristic peaks corresponding to the S^R state, whose energy depends on the deformation of the adatom. The height of the adatom on the nanoisland estimated from the energy difference is consistent with a result of the STM measurement. The strain of adatoms can be estimated from the electronic structure.

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  A thin silicon nanooverlayer (SNOL) fabricated by oxidation and etch-back in a Separation by IMplantation of OXygen wafer was investigated by grazing incident X-ray diffraction at incident angles between 0.01° and 0.1° below the critical angle of total reflection (0.18°). We measured {220} reflections by probing the sample with respect to surface normal and found that the SNOL has finite domains under strain close to the surface. We also found that annealing the sample up to 1000°C significantly reduced inhomogeneous strain and increased the size of the domains in the surface region of the SNOL.

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  Since the conventional strategy, namely scaling of device dimensions in ultimately scaled shorter-channel-length MOS transistors, is less effective to enhance transistor performance, another strategy is strongly demanded. Stress engineering is one of the most promising performance boosters for the ultimately scaled MOS transistors. In this paper, we will introduce the physical mechanisms of the drain current enhancement induced by stress. We will discuss the mechanisms based on the band structure modification by stress. The effectiveness of the stress engineering in future devices is also prospected.

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  The strain effect on the hole transport properties in Si p-MOSFETs was investigated theoretically. We have calculated the subband structure of the two-dimensional hole gas in inversion layers using an empirical pseudopotential method and a k•p perturbation theory. Based on the obtained subband structures, the hole transport characteristics, i.e., the low field mobility, the injection velocity, and the saturation velocity, were computed numerically. We compared the impacts of the various stress application methods (tensile/compressive strains along uniaxial/biaxial directions). In the case of the <110> channel fabricated on Si(100) surface, it was demonstrated that the MOSFET performance can be enhanced effectively by the uniaxial compressive strain. The physical mechanisms behind the effect of the strain on the hole transport properties was discussed in detail.

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  We have optimized the deposition conditions for fabricating Ti-Ni shape memory films by dc unbalanced magnetron sputtering using Taguchi method. The deposited films were annealed at 600°C for 60 min for crystallization and memorization into a flat shape after dissolving the Cu substrates. These films were subjected to DSC measurements and thermal cycling tests under a constant stress. The Joule heat induced shape memory behavior was also characterized by a specially designed tensile testing machine.
  The transformation temperature of Ni-rich films was found to be lower than RT. On the other hand, those of Ti-47∼49.4 at%Ni films were higher than RT, which means they can be expected to show the shape memory effect at RT. The Ti-47∼49.4 at%Ni films showed a perfect shape recovery under a constant stress by Joule heat of less than 0.1 J.

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  Formation of titanium silicide islands by the coadsorption of titanium and oxygen on a Si(001) surface is studied by means of scanning tunneling microscopy. When the coverage of titanium is at 2 ML, subsequent oxygen exposure at 973 K produces defects preferentially near the titanium silicide islands. On the other hand, when the coverage of titanium is at around 0.1 ML, step morphology is largely changed by oxygen exposure and subsequent annealing to 873 K. This phenomenon does not change with the heating process when the oxidation precedes the titanium deposition or vice versa. Mechanism of the enhanced step-retreat process is attributed to the desorption of SiO species promoted by titanium silicide islands.

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  The operation of high voltage equipments inside a satellite may trigger electric discharge if the pressure around them is above the threshold. In a thermal vacuum test, high voltage equipments are turned on after the vacuum gage outside a satellite indicates a safe level —below the threshold— to avoid electrical discharge. However, since a satellite has quite a few outgassing sources in it, along with the limited conductance, the internal pressure is higher than the external pressure. So there is a possibility that the internal pressure is still above the threshold even after the external pressure has gone below it. To find out if it is safe to judge when to turn on high voltage equipments solely from the gage outside a satellite, we measured the pressure of both inside and outside a satellite, by placing a vacuum gage in both places. Measurement results showed that the internal pressure remained above the threshold even after the external pressure had fallen below it. As a consequence, it is confirmed that in a thermal vacuum test the power supplying point is better to be judged upon the internal pressure for the case of a satellite with high voltage equipments.

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  Approximately 20~110 nm-thick Al-doped transparent conducting zinc oxide (AZO) films have been deposited on glass substrates at temperature of 200~300°C by pulse laser deposition (PLD) using ArF excimer laser (λ=193 nm). When fabricated at the substrate temperature of 260°C, 40 nm-thick AZO films showed the lowest resistivity of 2.61×10^-4 Ω•cm.

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