[en] The optical properties of spin-cast poly(3-butylthiophene) (P3BT) films have been determined from 1.2 to 5.0 eV by spectroscopic ellipsometry. Dielectric-function spectra ε = ε₁ + iε₂ with well-resolved vibronic shoulders were extracted by multilayer calculations from the ellipsometric data. The effect of annealing on ε is also reported. The ε spectra of the annealed films show an increase of oscillator strength and a redshift of the main peak, which indicates the growth of an ordered structure due to self-assembly of the polymer chains. This conclusion is confirmed by X-ray diffraction. Photo-oxidative degradation is also investigated. We found that both light and oxygen are essential in causing degradation. The changes in conjugation length of degraded polymers on exposure are directly reflected in ε and can be parameterized in terms of the decreasing value of the main peak in ε₂. We also noticed that the film thickness increases on exposure, suggesting decreased film density. - Highlights: • Regioregular poly(3-butylthiophene) (P3BT) thin films prepared by spin-coating. • We report the dielectric function (ε) of P3BT thin films. • Effect of annealing on P3BT thin films in terms of ε is also discussed. • Photo-oxidative degradation of Annealed P3BT thin films is studied

[en] SMART(System-Integrated Modular Advanced Reactor) is an integral type advanced pressurized water reactor with a rated thermal power of 330 MW, developed at KAERI (Korea Atomic Energy Research Institute) for a seawater desalination and small scale electricity generation. Safety and economic improvement are the two most important considerations in the design of the SMART. The SMART design combines firmly established commercial reactor design technologies with advanced design features. The advanced design features and technologies implemented into the SMART design have been proven or will be qualified through the technology verification program of SMART. Technology verification program of SMART consists of basic thermal-hydraulic experiments, separate effect test, major components performance test, system integrated tests of safety system and one fifth scaled pilot plant construction project. The overall performance and safety of SMART will be demonstrated through the SMART-pilot plant (SMART-P). The SMART-P plant construction project is currently underway and will be complete the construction by 2010. (authors)

[en] We studied the surface structure of (001) InP in metalorganic chemical vapor deposition (MOCVD) ambient by surface photoabsorption (SPA). A P-dimer peak at 430 nm and an In-dimer peak at 600 nm were observed from the SPA subtraction spectra. A maximum SPA reflectivity change of 8 % between the P-stabilized and the In-stabilized surfaces was obtained at 470 nm. A first-order desorption kinetics was assumed to curve-fit the SPA signal and an activation energy of 3.36 eV was obtained

[en] In situ, real-time monitoring of InP atomic layer epitaxy (ALE) was performed in low-pressure metalorganic chemical vapor deposition (LP-MOCVD) by surface photoabsorption (SPA). A self-limiting adsorption condition was obtained from the trimethylindium (TMIn) decomposition experiment at various conditions. It was found that the growth rate was less than 1 monolayer (ML)/cycle. From the in situ, real-time SPA measurement during InP ALE, the incomplete PH₃ decomposition on the methyl-terminated In surface was attributed to the self-limiting submonolayer growth per cycle

[en] Dielectric functions as analytic functions of temperature are useful for nondestructive in-situ monitoring of material deposition and for device design. We present an analytic expression that accurately represents the dielectric function ε = ε₁ + iε₂ of InSb at energies from 0.74 to 6.42 eV for temperatures from 31 to 675 K. The original ε spectra were obtained by using rotating-compensator spectroscopic ellipsometry. We used the parametric model (PM), which can accommodate the asymmetric nature of critical-point features. The InSb data are successfully reconstructed with nine PM components and yield ε as a continuous function of both energy and temperature within the limits given above. Our results should be useful in a number of contexts, including device design and in-situ monitoring of deposition. A representative deposition example is discussed.

[en] We report an analytic expression for the dielectric function ε of GaN as a continuous function of energy from 0.74 to 6.42 eV and of temperature from 26 to 690 K. The ε spectra on which the analysis is based were obtained by using rotating-compensator spectroscopic ellipsometry. The dielectric function parametric model (DFPM) was used to provide the representation because it could accommodate the asymmetric nature of the features of the critical point. The GaN data could be successfully represented with three DFPM components and a pole and yielded ε as a continuous function of both energy and temperature over the ranges given above. Our results should be useful in a number of contexts, including device design and in-situ monitoring of GaN deposition.

[en] Self-assembled InAs quantum dots (SAQDs) were grown on InP by metalorganic chemical vapor deposition. The amount of excess InAs and the aspect ratio of the SAQD increased with temperature and V/III ratio. It is explained that the As/P exchange reaction at the surface played an important role in the kinetics of SAQD formation. Insertion of a lattice-matched InGaAs buffer layer suppressed the excess InAs formation, and lowered the aspect ratio. Moreover, the dots formed on InGaAs buffer layers were faceted, whereas those on InP were hemispherical, confirming the effect of the As/P exchange reaction. The shape of InAs quantum dots on InGaAs buffer layers was a truncated pyramid with four [136] facets and base edges parallel to <130> directions

[en] We report on the dynamics of bio molecules and a high polymer in a water environment by using imaging ellipsometry (IE). The morphology of collapsed films of arachidic acid (AA) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) Langmuir monolayers in a liquid solution is investigated. The IE images clearly show that the multilayer domains and thickness of the collapsed region change sensitively depending on Langmuir compression. Also, the adsorption of bovine serum albumin is observed by using total internal reflection resonance IE (TIRIE), which has the advantage of IE and surface plasmon resonance. We believe that IE is a powerful technique for analysis and applications of bio materials

[en] Data obtained by spectroscopic ellipsometry (SE) on a random array of oxide-coated InAs quantum dots (QDs) are analyzed by rigorous coupled-wave analysis (RCWA). RWCA is an important method of precisely determining the geometric parameters of patterned periodic structures, but has been applied only rarely to random systems and not previously to a random distribution of QDs covered with an oxide overlayer. We find our model calculations to be in reasonable agreement with data, showing that RCWA is a useful approach for extracting average values of the size, interval, distribution density, shape, and possibly composition of QD structures even when not periodically arranged.

[en] We report the parameters necessary to construct the dielectric functions of Cd_1-xMg_xTe ternary alloys at room temperature for arbitrary compositions from x = 0 to x = 0.5. The experimental spectra were measured by using vacuum ultraviolet spectroscopic ellipsometry in the spectral range from 0.7 to 9.0 eV. By performing a band structure calculation with the linear augmented Slatertype orbital method, we newly identify the four higher band gaps as E₂ + Δ₂, E₂(Δ), E₂(Σ), and E'₁ transitions.