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In modern extreme ultraviolet (EUV) lithography machines, sensitive optical components, such as multilayer mirrors and photomasks, may be affected by plasma interactions. The new 13.5 nm EUV-beam-line 2, designed to provide accelerated tests for next generation lithography, is used to investigate EUV-induced plasma phenomena. First systematic measurements of ion fluxes produced in EUV-induced hydrogen plasma are reported, with operating conditions including 5 and 20 Pa gas pressure, 3 kHz EUV pulse repetition rate, and 4.2 W total EUV beam power produced in a 10–15 ns EUV pulse. Space- and time-resolved distributions of ion fluxes and ion energies were measured using a retarding-field ion energy analyzer mounted next to the EUV beam. Typical ion energies were in the range of 1–8 eV and typical ion fluxes were in the range of 2–8 × 1017 ions m−2 s−1. The obtained ion fluxes are applied in a photomask lifetime test to understand the material effects after an EUV exposure. [ABSTRACT FROM AUTHOR]

Poly-p-phenylenebenzobisoxazole (PBO) is a fully conjugated, heterocyclic aromatic rigid-rod polymer having a collinear and coplanar backbone leading to excellent thermo-oxidative stabilities, mechanical tenacity, and optoelectronic properties. PBO is inherently a liquid-crystalline polymer and can be obtained as uniaxially oriented fiber or film by extrusion of acidic solution. Schemes for making uniaxial freestanding films and monolayered luminescence devices for polarized optical absorption and emission were processed from a uniaxial PBO fiber. Wide-angle x-ray scattering revealed that the starting fiber and the resulting films were highly oriented. UV-Vis transmission spectra over 200 to 800 nm indicated that the PBO films also had polarized absorption with an attenuation coefficient ratio α[sub ⊥]/α[sub ∥]=1.7. The photoluminescence (PL) of the PBO films was excited at 363 nm, showing an emission intensity ratio I[sub ∥]/I[sub ⊥] as high as 5. The anisotropic PBO film was sandwiched between an indium tin oxide substrate and an Al electrode for monolayer light-emitting diodes (LEDs), showing an electroluminescence (EL) intensity ratio I[sub ∥]/I[sub ⊥]=1.6 together with a markedly decrease in threshold voltage. PL and EL results demonstrated that a highly polarized luminescence emission was achieved by using the uniaxially oriented PBO films. The polarization effects in absorption and luminescence were absent for isotropic PBO films or LEDs. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Infrared spectra of CH stretches have been investigated on the surfaces of synthetic diamond crystallites (5, 100, and 700 nm in diameter) to provide insights into the mid-infrared emission bands of stardusts in interstellar media. While the spectrum of 5-nm diamonds fails to display the distinct 2835 cm-1 (or 3.53 μm) band, a remarkably good match of the absorption bands of larger diamond grains with the emission observed for the stars Elias 1 and HD 97048 is obtained. Suggested by this study, the nanodiamonds that can display such characteristic emission bands at 3.53 μm in these two interstellar systems have a size significantly larger than 5 nm. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a study that investigated low-temperature luminescent properties of heavily carbon- and zinc-doped gallium-arsenic grown by low-pressure metalorganic chemical vapor deposition. Luminescence linewidth; Appearance of a shoulder peak; Shift of the main peak to low energy.

Reports on the growth of In[sub0.49]Ga[sub0.51]P/gallium arsenide (GaAs) heterostructures by low-pressure metalorganic chemical vapor deposition. Examination of the zinc-induced disordering phenomenon by transmission electron microscope; Existence of electron gas in InGaP/GaAs heterjunctions; Preparation of samples.

Presents a study which investigated heavily carbon-doped gallium arsenide grown by low-pressure metal organic chemical vapor deposition using triethylgallium and arsine as sources and liquid carbon-tetrachloride as dopant. Methods for carbon doping in gallium arsenide; Method used in growing gallium arsenide; Properties of undoped gallium arsenide; Characteristics of doping concentration dependence of growth temperature; Growth rate and surface morphology of gallium arsenide.

The impedance of chemical vapor deposited CrO[sub 2] and Cr[sub 2]O[sub 3] bilayered thin films, composed of polycrystalline and amorphous structure, have been systematically studied in function of frequency and temperature. In the polycrystalline-CrO[sub 2]/amorphous-Cr[sub 2]O[sub 3] bilayer, the real part of impedance at low frequency (f<300 kHz) demonstrates a sharp transition at temperature around 330 K, with a specific feature of positive temperature coefficient, similar to the variation of dc resistance occurs at ferroelectric-paraelectric transition in the BaTiO[sub 3] ceramics. In contrast, the imaginary part of impedance, at frequency f>300 kHz, shows a characteristic of negative temperature coefficient. Further analysis of the frequency dependence of the impedance shows the contribution from the dynamics of both the dielectric and magnetic dipoles in the layers. Comparison of polycrystallineCrO[sub 2] and amorphous-Cr[sub 2]O[sub 3] single layer with the CrO[sub 2]/Cr[sub 2]O[sub 3] bilayer is discussed. [ABSTRACT FROM AUTHOR]

We report on the study of high frequency magnetotransport properties of the chromium dioxide (CrO[sub 2]) thin films, grown on Si substrate using chemical vapor deposition. The film exhibits a ferromagnetic transition with a Curie temperature near 390 K. The temperature dependent spontaneous magnetization follows Bloch's law. The impedance spectra, being analyzed based on the fundamental electrodynamics, are demonstrated to be in a low-loss dielectric limit along with the occurrence of dielectric relaxation and magnetization response. The specific features of impedance spectra, distinct from the usual metallic ferromagnet, are attributed to the half metallic nature of CrO[sub 2]. The results explore the possibility for high frequency device applications. [ABSTRACT FROM AUTHOR]

Presents a study concerning the anomalous mobility enhancement in heavily carbon-doped gallium arsenide. Methodology; Results of the study; Conclusion.

The small amplitude magnetohydrodynamic Riemann problem is studied using the Cohen–Kulsrud–Burgers equations. Unlike the coplanar Riemann problem, the evolution of noncoplanar Riemann problems is not self-similar and its flow structures could change in time. But its large-time behavior is very simple and a time-dependent 2→3 intermediate shock is always involved for the noncoplanar field rotations. The time-dependent 2→3 intermediate shock has a well-defined structure and exists for any degree of field rotation. [ABSTRACT FROM AUTHOR]

The Cohen–Kulsrud–Burgers equation (CKB) is used to consider the nonlinear evolution of resistive, quasiparallel Alfvén waves subject to a long-wavelength, plane-polarized, monochromatic instability. The instability saturates by nonlinear steepening, which proceeds until the periodic waveform develops an interior scale length comparable to the dissipation length; a fast or an intermediate shock then forms. The result is a periodic train of Alfvén shocks of one or the other type. For propagation strictly parallel to the magnetic field, there will be two shocks per instability wavelength. Numerical integration of the time-dependent CKB equation shows that an initial, small-amplitude growing wave asymptotes to a stable, periodic stationary wave whose analytic solution specifies how the type of shock embedded in the shock train, and the amplitude and speed of the shock train, depend on the strength and phase of the instability. Waveforms observed upstream of the Earth’s bowshock and cometary shocks resemble those calculated here. [ABSTRACT FROM AUTHOR]

A simplified set of equations is derived that approximates the magnetohydrodynamic (MHD) Navier–Stokes equations for weakly nonlinear disturbances whose speeds are close to the MHD intermediate speed. Its shock structure solutions are then examined. The fast and slow shock solutions are uniquely specified by their Rankine–Hugoniot relations. However, the intermediate shock solutions, which are not unique, are characterized by the integral through the shock of the noncoplanar component of the magnetic field. For situations in which this integral is conserved, the Riemann problem is well defined and predicts the evolution of intermediate shocks. This analysis is substantiated by numerical computations. [ABSTRACT FROM AUTHOR]

Instead of detecting electrical signals for diagnosing cardiac abnormalities, a promising alternative is to detect the magnetic signals generated from cardiac electrical currents. The system utilizing 64 low-transition-temperature superconducting quantum interference devices was tested to detect the time-dependent magnetocardiac signals that are spatially distributed over the heart. To achieve efficient acquisition and analysis, we propose a method to detect two-dimensionally, the T wave propagation of electromagnetic signals of beating hearts. In addition to characterizing the propagating behaviors, the differences between normal hearts and those with coronary artery disease were investigated. [ABSTRACT FROM AUTHOR]

In this work, we developed processes to biofunctionalize magnetic nanoparticles dispersed in phosphate buffer saline solution. For future clinical utility, magnetic nanoparticles were biofunctionalized with anti-vascular cell adhesion molecule-1 (VCAM-1) to label the VCAM-1 molecule, which served as an indicator for the lesions prone to vulnerable atherosclerotic plaque formation. The biofunctionalized magnetic nanoparticles were used to magnetically label, in vitro, cells expressing VCAM-1, as well as to locate the vulnerable aortic lesions of hypercholesterolemic rabbits with the aid of magnetic resonance imaging. In addition to demonstrating the feasibility of using biofunctionalized magnetic nanoparticles for biomolecule assays, the relevant physical mechanisms are discussed. [ABSTRACT FROM AUTHOR]

A spin-polarized vertical cavity surface emitting laser, with InAs/GaAs self-organized quantum dots as the active gain media, has been fabricated and characterized. Electron spin injection is achieved via a MnAs/GaAs Schottky tunnel contact. The laser is operated at 200 K and, at this temperature, the degree of circular polarization in the output is 8% and the maximum threshold current reduction is 14%. These effects are not observed in identical control devices with nonmagnetic contacts. [ABSTRACT FROM AUTHOR]

In this work, the authors used a superconducting quantum interference device (SQUID) magnetocardiography (MCG) system consisted of 64-channel low-transition-temperature SQUID gradiometers to detect the MCG signals of hepercholesterolemic rabbits. In addition, the MCG signals were recorded before and after the injection of magnetic nanoparticles into the rabbits’ ear veins to investigate the effects of magnetic nanoparticles on the MCG signals. These MCG data were compared to those of normal rabbits to reveal the feasibility for early detection of the electromagnetic changes induced by hypercholesterolemia using MCG with the assistance of magnetic nanoparticle injection. [ABSTRACT FROM AUTHOR]

In this work, we developed immunomagnetic detection techniques for detecting human C-reactive protein (CRP). To enhance the technique’s sensitivity to human CRP, biofunctionalized magnetic nanoparticles were used as markers, and a superconductive quantum interference device gradiometer system was adapted to measure the saturated magnetization of magnetically labeled CRP–anti-CRP immune complexes. Sensitivity for human CRP was found to be as high as 1 ng in 0.1 ml, i.e., 10 ng/ml in concentration. This sensitivity is much higher than that of conventional enzyme linked immunosorbent assay by one order of magnitude. [ABSTRACT FROM AUTHOR]

In addition to synthesizing biofunctionalized magnetic nanopaticles for the purpose of magnetically labeling biomolecules, a system to measure the ac magnetic susceptibility of the labeled sample was developed. When a targeted biomolecule was mixed with magnetic fluid possessing biofunctionalized magnetic nanoparticles, portions of magnetic nanoparticles agglomerated to form clusters due to the association with the targeted biomolecule. Due to the formation of magnetic clusters, the measured ac magnetic susceptibility reduced. The relationship between the mixed-frequency ac magnetic susceptibility reduction and the amount of the detected biomolecule was established. [ABSTRACT FROM AUTHOR]

We report the effects of In[SUB0.33]Ga[SUB0.67]As capping layers on the structural and optical properties of InAs self-organized quantum dots grown by gas-source molecular-beam epitaxy. With different deposition methods for the InGaAs capping layer, the quantum-dot density can be adjusted from 2.3 × 10[SUP10] to 1.7 × 10[SUP11]cm[SUP-2]. As-cleaved 3.98-mm-long diode laser using triple stacks of InAs quantum dots with the capping layer grown by GaAs/InAs sequential binary growth demonstrates an emission wavelength of 1305 nm and a threshold current density of 360 A/cm[SUP2]. A ground-state saturation gain of 16.6 cm[SUP-1] is achieved due to the high dot density. [ABSTRACT FROM AUTHOR]

A "fuzzy-junction" organic light-emitting device (OLED) containing a graded organic-organic interface is reported. Such graded junction is effectively produced utilizing interdiffusion through an ultrathin interfacial fusing layer sandwiched between two functional layers. With a glass transition temperature (T[sub g]) lower than remaining layers, this fusing layer permits smooth interdiffusion and mixing of neighboring layers by annealing above its T[sub g]. With appropriate material combinations, fuzzy-junction OLEDs thus prepared exhibit both reduced voltage and enhanced emission efficiency in comparison with conventional abrupt-junction devices. As an instance, a green fluorescent OLED with such fuzzy junction shows a high peak power efficiency of ∼20 lm/W, substantially higher than ∼14 lm/W of a corresponding abrupt-junction device. A "fuzzy-junction" organic light-emitting device (OLED) containing a graded organic-organic interface is reported. Such graded junction is effectively produced utilizing interdiffusion through an ultrathin interfacial fusing layer sandwiched between two functional layers. With a glass transition temperature (T[sub g]) lower than remaining layers, this fusing layer permits smooth interdiffusion and mixing of neighboring layers by annealing above its T[sub g]. With appropriate material combinations, fuzzy-junction OLEDs thus prepared exhibit both reduced voltage and enhanced emission efficiency in comparison with conventional abrupt-junction devices. As an instance, a green fluorescent OLED with such fuzzy junction shows a high peak power efficiency of ∼20 lm/W, substantially higher than ∼14 lm/W of a corresponding abrupt-junction device. [ABSTRACT FROM AUTHOR]

An efficient and morphologically stable pyrimidine-containing spirobifluorene-cored oligoaryl, 2,7-bis[2-(4-tert-butylphenyl)pyrimidine-5-y1]-9,9'-spirobifluorene (TBPSF), as an emitter or a host for blue organic light-emitting devices (OLEDs), is reported. The steric hindrance inherent with the molecular structure renders the material a record-high neat-film photoluminescence (PL) quantum yield of 80% as a pure blue emitter (PL peak at 430 nm) of low molecular weight, and a very high glass-transition temperature (T[sub g]) of 195°C. Blue OLEDs employing this compound as the emitter or the emitting host exhibit unusual endurance for high currents over 5000 mA/cm². When TBPSF is used as a host for perylene in a blue OLED, maximal brightness of ∼80 000 cd/m² had been achieved, representing the highest values reported for blue OLEDs under dc driving. [ABSTRACT FROM AUTHOR]

Organic poly(p-phenylenebenzobisthiazole), PBT, is spin coated on n-GaN epilayer to serve as a gate insulating layer. The GaN is grown on c sapphire by the metalorganic-chemical-vapor-deposition method. A metal-insulator-semiconductor structure is fabricated with Al ohmic contact to the n-GaN, and Au/Al gate metal on top of the PBT. High-frequency capacitance measurements are performed. A doping concentration of 8.2×10[sup 16] cm[sup -3] is obtained from the capacitance in the depletion region as compared with a Hall value of 7.8×10[sup 16] cm[sup -3]. Another technique of max–min capacitance method is also used in the calculation of the doping concentration. The threshold voltage is calculated as -5.1 V, and negative charges with an effective charge number density of 9.3×10[sup 11] cm[sup -2] shift the capacitance curve towards the positive voltage side. The hysteresis phenomenon is observed and analyzed. The current–voltage curve shows a low, constant current value up to 20 V. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this letter, we report a promising type of electrically programmable, i.e., reconfigurable, organic light-emitting devices (OLEDs) incorporating a thin carrier-blocking layer as the sacrificial fusing layer. In such devices, the carrier-blocking layer has a lower glass transition temperature than neighboring layers. By raising the internal temperature of the device above the transition temperature of the carrier-blocking layer with a large enough current, interdiffusion between organic layers could occur through such a layer. As a consequence, neighboring layers are fused and a new path for carrier transport is formed, bypassing the carrier-blocking property and altering the device characteristics. A device that emits blue light as fabricated but can be transformed into a green-emitting one is demonstrated. Such a type of device may be used for color pixels in OLED displays, user-programmable OLED applications, and nonvolatile memory devices.© 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Behaviors of an excess proton in solute-containing water clusters were investigated using infrared spectroscopy and ab initio calculations. This investigation characterized the structures of protonated methanol-water clusters, H[sup +](CH[sub 3]OH)(H[sub 2]O)[sub n] with n=2-6, according to their nonhydrogen-bonded and hydrogen-bonded OH stretches in the frequency range of 2700-3900 cm-1. Ab initio calculations indicated that the excess proton in these clusters can be either localized at a site closer to methanol, forming a methyloxonium ion core (CH[sub 3]OH[sub 2][sup +]), or at a site closer to water, forming a hydronium ion core (H[sub 3]O[sup +]). Infrared spectroscopic measurements verified the calculations and provided compelling evidence for the coexistence of two distinct structural isomers, CH[sub 3]OH[sub 2][sup +](H[sub 2]O)[sub 3] and H[sub 3]O[sup +](CH[sub 3]OH)(H[sub 2]O)[sub 2], in a supersonic expansion. The spectral signatures of them (either CH[sub 3]OH[sub 2][sup +] or H[sub 3]O[sup +] centered) are the free-OH stretching absorption band at 3706 cm-1 of a single-acceptor-single-donor H[sub 2]O, and the band at 3673 cm-1 of a single-acceptor CH[sub 3]OH. At n=4-6, the clusters adopt structures similar to their pure water analogs with five-membered rings starting to form at n=5. The position of the excess proton in them varies sensitively with the number of solvent water molecules as well as the geometry of the clusters. To further elucidate the behaviors of the excess proton in these clusters, we analyze in detail the potential energy surface along the proton transfer coordinate for two specific isomers of n=2 and 4: MW2II and MW4I. It is found that the proton can be nearly equally shared by methanol and the water dimer subunit in the form of CH[sub 3]OH-H[sup +]-(H[sub 2]O)[sub 2], as substantiated by hydrogen bond cooperativity and zero-point vibrational effects. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Presents a method for improving the efficiency, brightness, and reliability of organic light emitting devices of indium tin oxide using plasma treatment. Correlation among indium tin oxide (ITO) surface properties; Effect of ITO treatments to voltage of the bipolar current; Significance of plasma treatments in surface morphology.

We report a demonstration of the integration of individual polymer-based light emitting devices of three different colors on the same substrate. Orange, green, and blue color devices are sequentially fabricated on the same indium–tin oxide (ITO) coated glass substrate coated with a patterned insulator on the ITO, by the spin coating of polymer thin films, the vacuum deposition of top metal contacts, and the patterning of polymer thin film by plasma etching, using the top metal contacts as the self-aligned etching mask. The devices exhibit no degradation of device characteristics due to the integration processing compared to discrete devices on separate substrates. This demonstration shows a new path towards the fabrication of high performance low-cost full-color organic flat panel displays. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

GaN films with Ga or N face and of n- or p-type doping were grown by plasma-assisted molecular-beam epitaxy. The wurtzite GaN exhibits a large polarization, with spontaneous and piezoelectric components. The direction of polarization, and thus polarization-induced electric fields, Fp is determined by the polarity of the sample. Contactless electroreflectance (CER) has already been employed to study the nature of band bending in GaAs samples. In this work, CER is used to study the band bending of the GaN samples. It was found that the phase of CER is determined by the type of doping, rather than by the polarity of the surface. Additionally, the photoreflectance (PR) spectra were also measured. Comparing CER with PR determines the type of doping. [ABSTRACT FROM AUTHOR]

Ink-jet printing was used to directly deposit patterned luminescent doped-polymer films. The luminescence of polyvinylcarbazol (PVK) films, with dyes of coumarin 6 (C6), coumarin 47 (C47), and nile red was similar to that of films of the same composition deposited by spin coating. Light emitting diodes with low turn-on voltages were also fabricated in PVK doped with C6 deposited by ink-jet printing. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A theory of sonoluminescence has been developed based on the compression and eventual ionization of air in a bubble by the converging shock waves generated by the applied acoustic radiation. The air is compressed to such high densities that departures from the ideal gas law become very significant. An extension to the van der Waals gas has been made to the similarity theory of Guderley for the structure of spherical shocks in an ideal gas. The linear stability of these shocks has also been examined. [ABSTRACT FROM AUTHOR]