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Nanoimprint is an emerging lithographic technology that promises high-throughput patterning of nanostructures. Based on the mechanical embossing principle, nanoimprint technique can achieve pattern resolutions beyond the limitations set by the light diffractions or beam scatterings in other conventional techniques. This article reviews the basic principles of nanoimprint technology and some of the recent progress in this field. It also explores a few alternative approaches that are related to nanoimprint as well as additive approaches for patterning polymer structures. Nanoimprint technology can not only create resist patterns as in lithography but can also imprint functional device structures in polymers. This property is exploited in several non-traditional microelectronic applications in the areas of photonics and biotechnology.

Electron holography (EH) has been used successfully for studying the barrier shape profiles and barrier/electrodes interfaces in a magnetic tunnel junction (MTJ) that was fabricated with a wedge-shaped Al oxide barrier, and an asymmetrical curve of the tunnelling magnetoresistance (TMR) versus nominal Al thickness has been found. EH results reveal several useful features that are unlikely to be found using other techniques. The asymmetrical TMR curve and the TMR value unachievable with Jullière model are mainly due to the different barrier/electrode interfaces along the wedge. Furthermore, a model of barrier oxidation has been built to explain the TMR behaviour in MTJs.

A series of Co_x(Cr₂O₃)_1−x granular films with various Co volume fractions x (x = 0.15–0.55) have been fabricated by RF co-sputtering. X-ray diffraction, transmission electron microscopy, energy dispersive x-ray and x-ray photoelectron spectrometer have been employed to characterize the structure, composition and element valence. VSM and the conventional four-point resistance measurement method have been used to investigate the magnetic and electrical properties. It is found that the films consist of Co particles with an average size of about 5 nm distributed in an amorphous Cr₂O₃ matrix for x = 0.35. The isotropic tunnelling magnetoresistance (TMR) is obtained. TMR increases with decrease in x from 0.55, reaches a maximum of 5.1% at x = 0.35, then decreases with further decrease in Co volume fraction. This behaviour can be explained by the film microstructure variation and conductive mechanism. What is interesting is that TMR becomes negative, −3.5%, for the x = 0.15 sample. This behaviour was also observed in Fe–Cr–O granular films with the lowest Fe volume fraction (x = 0.15). This change in the sign of TMR implies that the barrier thickness of the metal–insulator–metal junction plays an important role in the determination of the spin polarization of tunnelling electrons.

The cross section set of perfluorocyclobutane (c-C₄F₈) is determined by the electron swarm method. The modification is applied to the vibrational excitation cross section and the elastic momentum transfer cross section. Our previously measured electron swarm parameters (drift velocities, longitudinal diffusion coefficients and effective ionization coefficients) in 0.468% and 4.910% c-C₄F₈/Ar mixtures are used for the determination of the vibrational excitation cross section. The measured drift velocity and longitudinal diffusion coefficient in pure c-C₄F₈ are used to determine the correct elastic momentum transfer cross section. The calculated electron transport coefficients were derived using the Monte Carlo simulation method.

Bremsstrahlung coefficients for electron–mercury-atom collisions were computed using the corrected phase-shift approximation. These corrected bremsstrahlung coefficients are a weighted average of coefficients from the phase-shift and momentum transfer approximations. Phase-shifts determined from solutions of the Dirac–Fock scattering equations including both static and dynamic polarization potentials and exchange effects were used. The corrected coefficients approach the same limit at longer wavelengths as coefficients from the simpler momentum transfer approximation, but are generally larger.

A novel rf microplasma jet at atmospheric pressure was successfully generated using a single needle tube electrode. The atmospheric He discharge was characterized using optical emission spectroscopy with the inner hole diameter of the needle electrode and the flow rate of gas as variables. Preliminary results of the application of microplasma jets to thin film processing are given, i.e. silicon oxidation and the synthesis of carbon nanostructures including amorphous carbon, graphite, and nanotubes. A metal-oxide-semiconductor structure using the silicon oxidized layer formed by the O₂/He plasma showed good rectification behaviour. The effects of gas flow velocity and inner diameter of the needle tube electrode on the carbon nanostructure and deposition area are discussed.

This article was due to be published in Volume 36, issue 23 of Journal of Physics D: Applied Physics. To access this special issue please follow this link http://www.iop.org/EJ/toc/0022-3727/36/23

GaN crystalline films were grown on SiC and Si substrates by molecular beam epitaxy. Er doping was carried out by ion implantation at an energy of 180 keV with fluences from 5 × 10¹³ to 5 × 10¹⁵ ions cm⁻². The as-implanted samples were then annealed at 650°C, 800°C, 950°C and 1100°C, respectively. The annealing at temperatures as high as 1100°C did not exert any influence on implant-induced lattice damage. After annealing all the samples gave a PL signal at 1.54 µm. The most intensive PL emission came from the sample annealed at 950°C. Annealing at 1100°C resulted in the diffusion of Er ions and ion aggregation near the film surface, which degraded the photoluminescence from Er ions significantly. After annealing at temperatures higher than 800°C, an oxide layer was formed on the surface of GaN and high temperature annealing at 1100°C results in both a rough film surface and nonuniform distribution of ions, which has been investigated by transmission electron microscope.

Oriented thin films of La_0.67Sr_0.33MnO₃ and La_0.67Ca_0.33MnO₃ were fabricated on a SrTiO₃(002) single crystal substrate by the chemical solution deposition (CSD) process. The CSD grown films have electronic and magnetotransport properties which are comparable to those of films prepared by the pulsed laser technique and to those of the bulk single crystal samples. The magnetoresistance of the films was found to be very similar to those of pulsed laser deposition grown films and they show no contribution of grain boundaries unlike polycrystalline films. The atomic force microscopy study of the roughness and its scaling with length shows that the surfaces of the films are self affine.

Low-emissivity coatings on glass, which provide highly efficient heat isolation, are nowadays extensively used in windows in offices and residential buildings for the purpose of saving energy in air conditioning. In this paper, multilayer low-emissivity coatings with the structure glass/SnO₂/Ni–Cr/Ag/Ni–Cr/SnO₂ were deposited onto large glass substrates in an industrial sputtering system. The extremely low thickness of the layers which compose such structures, as well as the large substrate area, causes the structure and impurity content of the films and interfaces to play an important role in providing efficient energy-saving performance as well as high optical transmittance. Thus, in-depth characterization was performed by spectroscopic ellipsometry, Rutherford backscattering spectroscopy and Auger electron spectroscopy. The use of these characterization techniques provides the great advantage of allowing the investigation of the whole multilayer system, including the interfaces. However, the properties of the individual layers (density, composition and optical behaviour) were also determined independently and compared to the values of corresponding bulk materials. Special attention is devoted to inter-diffusion of species.

The effects of saturated organic vapours on spun thin films of the conjugated polymer of regioregular poly[3-(6-methoxyhexyl)thiophene] molecules were investigated by using the surface plasmon resonance technique in a Kretschmann type optical arrangement. The refractive index of the untreated polymer film is found to be 1.505 irrespective of the film speed. The swelling of the film occurs due to benzene exposure and a small change of refractive index is also observed, possibly due to the influence of benzene on the orientation ability of the polymer. The vapour response is related to the magnitudes of the vapour dipole moments and their sizes. The polymer suffers irreversible degradation due to the continuous exposure to ozone concentrations in the ppb range.

We have studied the anisotropy of the photoluminescence (PL) of InGaP films grown by liquid phase epitaxy on GaAs substrates. The PL measurements were performed in a wide temperature range (4–250 K) and exciting power density range for polarizations of the emitted radiation along the [011] and [ ] directions. It was found that the donor–acceptor transition dominates at low temperature (4 K) while the band-to-band transition dominates at a higher temperature (250 K). The dependence of PL intensity on excitation intensity shows a characteristic behaviour for donor–acceptor recombination. The difference in the position of the spectral peak for [011] and [ ] polarizations is a result of the splitting of the valence-band into heavy- and light-hole bands due to strain. Moreover, the difference in the line shape of the spectra for different polarizations indicates the presence of anisotropy for different crystallographic directions.

SiO₂ thin films have been obtained by 1064 nm Nd : YAG laser oxidation of p-Si in the presence of O₂. The thickness uniformity, dielectric and electrical properties of the layers have been studied. The effect of both the laser beam energy density and the substrate temperature on the oxide growth is also discussed. It was established that there exists an interval of laser beam energy density in which the oxidation occurs without surface melting. The oxidation process is controlled by the laser beam energy density rather than by the substrate temperature (673–748 K) and the higher laser power results in a thicker oxide. X-ray photoelectron spectroscopy (XPS) was used to provide information on the oxide composition. XPS results revealed that the as-grown oxide is a mixed layer of SiO₂ and Si₂O, which are distributed nonuniformly through the depth. MOS capacitors fabricated on the grown oxide exhibited typical capacitance–voltage, conductance–voltage characteristics. However, the density of interface states and oxide charge density were found to be higher than the typical values of thermally grown oxides. The quality of the oxide layers can be further improved by optimization of the process parameters and/or by post-processing of the grown films. It is concluded that the SiO₂ films formed by the technique of Nd : YAG laser-enhanced oxidation at low temperature are potentially useful for device applications.

The effective piezoelectric coefficients of novel 0–3 'relaxor-ferroelectric Pb(A_1/3B_2/3)O₃–PbTiO₃-type single-crystal–ferroelectric PbTiO₃-based ceramic' and 0–1–3 'relaxor-ferroelectric Pb(A_1/3B_2/3)O₃–PbTiO₃-type single-crystal–ferroelectric PbTiO₃-based ceramic–polymer' composites are determined at various volume concentrations of piezo-active components. The role of the piezo-active single-crystalline and ceramic components in the non-monotonic concentration dependence of the piezoelectric properties of these composites is analysed. First, some empirical relationships among electromechanical constants of the components are given and discussed, which guarantee considerably high values of the hydrostatic piezoelectric coefficients and of the above-mentioned 0–3 composites with spheroidal inclusions. Next, it is shown that the presence of the relaxor-ferroelectric component in the 0–1–3 composite results in an unusual concentration behaviour of its piezoelectric coefficients and , which has not been described before in papers on the well-studied 1–3 'ferroelectric ceramic – polymer' composite. Examples of the large piezoelectric anisotropy of the 0–1–3 composite (i.e. conditions , , and , where are electromechanical coupling factors) are also considered and discussed.

A simple table-top windowless system for extreme ultraviolet (XUV) spectroscopy which avoids differential pumping for both the radiation source and the detector is presented. The radiation source uses excimer emission from rare gases excited with low energy (13 keV) electron beam. Broadband emission in the entire wavelength range from 60 to 140 nm is demonstrated using He, Ne and a Ne–Ar gas mixture. It was observed that the so-called third continuum is absent in Ne when low energy electron-beam excitation is used in contrast to earlier results using high energy ion beam excitation. An application of the set-up for a LiF transmission measurement close to the cut-off wavelength (105 nm) is demonstrated. It is shown how the radiation source could be applied in a simple and efficient technique of material treatment with XUV/VUV radiation.

The self-inductance for a twisted bifilar lead is investigated as a function of the twist pitch, as an extension of that for a straight bifilar lead. This calculation method for inductance is based on the numerical integral calculation of the magnetic energy, using the analytical expressions for the vector potentials due to a single helical thin conductor. The calculated results are compared with the experimental measurements, and reasonable agreement is observed.