Reiko Yoshimura

Frequency-dependent polarizabilities, hyperpolarizabilities, and excitation energies from time-dependent density-functional theory based on the quasienergy derivative method

A time-dependent density-functional theory for systems in periodic external potentials in time is formulated on the assumption of the existence of the Floquet states from the quasienergy viewpoint. Coupling strength integration, which connects a noninteracting system with an interacting system, is introduced by using the time-dependent Hellmann–Feynman theorem. Coupled perturbed time-dependent Kohn–Sham equations are derived from the variational condition to the quasienergy functional with respect to parameters. Explicit expressions for frequency-dependent polarizability and first hyperpolarizability are given by the quasienergy derivative method. Excitation energies and transition moments are defined from poles and residues of frequency-dependent polarizabilities, respectively. In contrast to the previous theory, our formulation has the following three advantages: (1) The time-dependent exchange-correlation potential is defined by the functional derivative of the exchange-correlation quasienergy. (2) The...

Ab initio molecular orbital study on the reaction of TMA with H2

Abstract The reaction of trimethylaluminium (Al(CH 3 ) 3 , TMA) with H 2 has been investigated using ab initio molecular orbital calculations. It has been shown that the activation energy of the reaction, TMA + H 2 → AlH(CH 3 ) 2 + CH 4 , is about 1/2 of the dissociation energy of radical decomposition, TMA → Al(CH 3 ) 2 + CH 3 . This means that TMA decomposition under conditions where collisions between TMA and H 2 are sufficiently frequent is dominated by hydrogenolysis. This explains the experimental result that the decomposition temperature of TMA becomes lower with increasing H 2 pressure.

Ab initio MO studies on dissociative electron attachment of vinyl chloride. The simplest chlorine-containing hydrocarbon having a CC π system

Abstract The potential energy surface of the vinyl chloride radical anion, which is the simplest chlorine-containing hydrocarbon anion having a CC π system, has been studied by ab initio molecular orbital theory. The calculated results indicate that the initial 2 Π state is rapidly changed to the repulsive 2 Σ state by a CCl out-of-plane deformation during CCl dissociation. While no metastable 2 Π state is found on the potential energy surface, the same kind of planar metastable weak complex is found on the minimum energy path as in the case of the methyl chloride radical anion. The differences and similarities between the CCl dissociation minimum energy paths of the vinyl chloride and methyl chloride radical anions are also discussed.

Novel model of haze generation on photomask

ArF lithography sometimes generates the haze defects on the photomask substrate, resulting in serious yield deterioration in ULSI production. In order to solve this problem, experimental and theoretical studies have been carried out on the generated haze defects. In characterizing the haze defects, the composition and chemical structure of the haze defects were analyzed by focusing on 1.0 x 0.3μm sizes defects using Raman, ToF-SIMS and AES spectroscopy with their highest spatial and mass resolution level. To confirm the experimental analyses, theoretical ab initio molecular orbital calculations were carried out on the model compounds of the generated haze defects. These experimental and theoretical studies indicate that the haze defects on quartz surface consist of (NH4)2SO4 and that those on half-tone (HT) film surface, on the other hand, consist of (MoO3)x(SO4)y(NH4)z complex including Mo from HT film material. In the latter case, NH4 ion was observed only in surface region of the haze defects. Based on these results, we have proposed a novel model of haze generation mechanism on quartz and HT film surfaces of photomask substrate.

Theoretical studies on hydroxylation mechanism of H-terminated Si surface in aqueous solutions

Abstract The hydroxylation mechanism of the H-terminated Si surface in aqueous solutions has been theoretically studied by a quantum chemical approach. OH − ion instead of H 2 O plays a dominant role in the surface hydroxylation, where two different reaction pathways exist. One of them is accompanied with the SiSi back bond cleavage. The high reactivity of the residual surface SiF bonds is also discussed.

Metallic Contamination Control in Leading-Edge ULSI Manufacturing

Contamination control has become a high-centered issue for the fabrication yield, performance and reliability of leading-edge ULSI devices. With the progress of sizing down dimensions in higher-density devices, complicated device structures and various novel electronic materials have been introduced, particularly in the latest devices such as CMOS and nonvolatile memory LSIs (Table I). On the other hand, high productivity is a necessity when you consider QTAT (quick turnaround time) and cost-effective flexible ULSI manufacturing lines. Therefore, effective contamination control coupled with adequate protocol has become essential in such production lines. The point of the protocol is minimization of damage caused by impurity metals diffused from these novel electronic materials [1-5].

Ab initio molecular orbital study on thermal decomposition of tertiarybutylphosphine

The thermal decomposition process of tertiarybutylphosphine (C(CH3)3PH2, TBP) has been investigated by ab initio molecular orbital calculations. It has been shown that the radical process, TBP→C(CH3)3+PH2, is the energetically most favorable process among the processes which are effective for metalorganic chemical vapor deposition. The calculated dissociation energy of TBP was smaller than that of PH3. This result explains the experimental results that the growth temperature is lower for the use of a TBP source than for a PH3 source.

Comparative study of electronic states of VO6 and CuO6 clusters

Abstract The electronic structure of layered-perovskite oxides Srn+1VnO3n+1 (n = 1, 2, 3) is investigated through ab initio molecular-orbital calculations for VO6 model clusters. The results are compared with those for the CuO6 clusters in high-Tc cuprate superconductors. A number of causes, which may suppress superconductivity in the layered vanadium oxides, are suggested.

Electronic Structure of Vanadium Oxide Clusters in Layered Perovskite Compounds Srn+1VnO3n+1(n=1, 2, 3)

The electronic structures of layered-perovskite oxides Sr n +1 V n O 3 n +1 ( n =1, 2, 3) have been analyzed through ab initio molecular-orbital calculations for VO 6 clusters, using the Hartree-Fock method followed by Moller-Plesset perturbation and configuration-interaction corrections. Comparisons of the electronic states have been made among VO 6 , CuO 6 and CuO 4 clusters to study the possibility of realizing vanadate superconductors on the analogy of the high- T c cuprate superconductors. Hole- and electron-doped states have also been investigated as well as the undoped state. We thus clarify a number of similarities and differences between the vanadates and the cuprates. It is also suggested that some of these differences may prevent the layered vanadium oxides from becoming high- T c superconductors.

Fabrication of metal core and organic shell nanoparticle packing film for plasmon polariton waveguide

Core-shell Au nanoparticles were synthesized for chemical reaction under mild liquid phase condition. The nanoparticles film was fabricated on a glass substrate for surface plasmon polariton waveguide. The nanoparticle piled up on the substrate made a smooth surface. A waveguide was easily fabricated by the lift-off method and the patterned trench filled method.