The resistance R of Fe, Pt and Cu films deposited by Ar ion beam sputtering was measured in situ and transmission electron micrographs of samples of different thicknesses were taken to identify the stages of film growth. A digital image processing technique was used to obtain the fractional coverage x as a function of film thickness t. Three stages of film growth are identified; the discontinuous and semicontinuous stages are modelled using a resistance network (10 × 10 grid) that represents the film for x < 1 by equivalent resistors whose values depend on the grid intercepts with the film. The continous regime is associated with t ≥tmin where tmin is the minimum that occurs in the R(t) measurements when plotted as Rt2 vs. t.tmin is shown to give a good indication of the onset of continuous film behaviour which first occurs at the point tx=1, i.e. when the film completely covers the substrate.

The resistance R(f) of Pt and Ni films has been measured during deposition (by ion-beam sputtering) for different deposition rates r and substrate temperatures T(S) (300 less-than-or-equal-to T(S) less-than-or-equal-to 575 K). At the onset of deposition (the nucleation stage) R(f) varies only slowly with deposition time T and oscillations occur in R(f) vs T which are damped at the larger values of r, T(S). Over the second stage, during which the metallic nuclei grow in size, R(f) decreases over many orders of magnitude and the R(f) versus fractional coverage x behavior is described by percolation-type equations around a critical thickness t(c). The film thickness t(min) (=rT(min)) at which the film becomes continuous (x = 1) is identified with the minimum in the Rt2 vs t graph. For t > t(min) the R(f) vs t behavior is described by surface and grain-boundary scattering equations, the derived values of grain size are related to T(S), r, and compared with transmission electron microscope observations. Postdeposition temperature cycling measurements on films deposited at T(S) = 300 K show predominantly thermally activated conduction for t < t0 (t(c) < t0 < t(min)). Rf is decreased by annealing, except in the case of Pt (t < 1 nm) and Ni (t less-than-or-equal-to 1.5 nm), due to agglomeration and the formation of conducting links which also change the temperature coefficient of resistance.

Ultrathin metallic films deposited on amorphous substrates show island growth until electrical percolation occurs. Scaling theory makes rather precise predictions about the deposition-time dependence of the island-size distributions and related properties. It is therefore important to be able to analyze experimental data in a quantitative way in order to be able to make a detailed comparison with theory. This paper addresses two aspects of the data analysis of island-size distributions. In the first, a robust method of presenting measurements in the form of continuous distributions (as opposed to histograms) is examined. In the second, we obtain a prescription for transforming chord distributions into diameter distributions. This transformation will be useful in cases where the islands are (or approximate to) regular droplets and when it is easier to measure chords than diameters. Relations between the moments of the chord and diameter distributions are obtained. To demonstrate the first method, it is used to extract the island-size distribution within a Pt/a-C film. A remarkably good match to a log-normal distribution is found without making any of the usual a priori assumptions. Comments on implications for scaling theory are made.

The nucleation and growth of Pt and Ni films deposited on amorphous carbon (a-C) substrates by ion-beam sputtering (IBS) have been followed from an early stage through to complete substrate coverage. The influence of IBS parameters and substrate temperature Ts on deposition rate and metal particle (island) size distributions have been measured. Metal island growth is shown to be predominantly two dimensional in character. Soft-x-ray reflectivity measurements on Ni/a-C multilayers detect the single atom layer increments in Ni island thickness tNi′ during growth from the initial (critical) value tNi′ = 0.87 nm which is consistent with a theoretical 22 atom cluster model. The influence of the metal island growth stages on the soft-x-ray reflectivity of multilayer mirrors is considered.

Mathematical models of interfacial roughness and interlayer diffusion and reaction, incorporated into the multilayer matrix method, in multilayer reflectors used in soft x-ray and EUV regions are created and discussed. Simulations on typical multilayers (e.g. Pt/a-Si, Pt/a-C and Ni/a-C) have revealed that the interfacial roughness reduces the peak reflectivity of a multilayer without a change of peak position, while the interlayer diffusion and reaction not only reduce the peak reflectivity sometimes (especially when diffusion occurs) but also shift the peak position. The interlayer diffusion causes more drastic change in multilayer performance than the interlayer reaction. The simulations on 'ideal' multilayer reflectors of commonly used materials (Pt, Mo, W, Ni, Cu) in conjuction with a-Si or a-C have also led to a recommended selection guide for material combinations over the wavelengths 3 less-than-or-equal-to lambda less-than-or-equal-to 100 nm. It is suggested however, based on simulation and practical considerations, that metal/a-C offers better thermal stability and hence is a better choice than metal/a-Si, especially in short-wavelength applications, though metal/a-Si sometimes provides higher 'ideal' peak reflectivity.

Transmission electron microscope observations have been made on ion beam sputtered (IBS) films of Cu, Au, Pt and Ni (of predetermined thicknesst′ ⩾ 0.5 nm) deposited on amorphous carbon substrates. The influence of IBS parameters on particle size distribution and deposition rate has been measured, also the fractional substrate coveragef as a function oft′ which indicates three-dimensional island growth in Au, Cu films and two-dimensional growth in Pt, Ni films. Electron diffraction measurements appear to show that the f.c.c. metal particles grow with (1 1 0) parallel to the substrate with, in the case of Ni, a critical island thickness of ∼ 0.8 nm.

Near-normal incidence mirrors for wavelengths u < 10 nm may be fabricated from metal-a-C multilayers in which the metal film thickness t r 2·5 nm. The growth of such thin non-epitaxial metal films proceeds from a nucleation stage via island growth to the continuous film. Reflectivity measurements on Ni-a-C multilayers show that the metal film growth stages displace, split and greatly reduce the expected intensity of the first-order multilayer reflections. These effects are analysed in terms of the atomic growth of the metal islands which appear to set a short wavelength limits uc * 3·2 nm on the normal incidence multilayer reflectivity.

Near normal incidence imaging optics for use at wavelengths A in the 'water window' (2.4X4.4nm) utilise the in-phase reflections from a multilayer stack deposited on a figured substrate. The reflectivity of such a multilayer depends upon the number N of contributing interfaces and the amplitude reflectivity r at each interface where r M + ituz is determined by the difference in the real and imaginary parts of the refractive indices of the media defining the interface. Thus r may be predominantly determined by (Class I) or & (Class II) or a combination of both (Class III). The spectral variation of r (2 .3X4 .8nm) has been computed for interfaces formed by a-C and fifty four different elements which are thereby classified as I, II or III. The normal incidence reflectivity R versus A of representative multilayers from each class has been calculated as a function of N and layer thickness ratio 'y and criteria established for the most suitable choice of layer materials for the 'water window' region. In practice the particulate nature of the thin metal film components of the multilayer results in the experimental values of R being much less than the theoretical values.

At short wavelengths (λ - 5nm) a highly reflecting multilayer must consist of a large number of layers, in which the layer interfaces are sharply defined and the strongly absorbing (metal) component layers are as thin as possible. The mininum thickness of a microcrystalline metal layer is apparently set by the unit cell dimensions, the lateral dimensions of each microcrystallite, by the deposition conditions and nature of the metal. The influence of these parameters is described and related to the fabrication of short wavelength reflecting mirrors.

The reflectivities of plane Pt-Si multilayer mirrors of various d spacings and layer thickness ratios have been measured as a function of angle, at wavelengths within the soft X-ray and EUV regions. The measured performance is compared with theory and the effect of heat treating the mirrors interpreted in terms of Pt film agglomeration. The imaging characteristics of a concave Pt-Si multilayer mirror are presented.

Injection-moulded plaques of polystyrene and of two types of high-density polyethylene have been produced under different moulding conditions. Microscopic examination coupled with birefringence measurements on polystyrene and polyethylene show that the plaques contain a flow-induced molecularly ordered structure together with, in the case of polyethylene, a thin (∼4µm) disordered surface layer. Thermal annealing of the polystyrene birefringence and “frozen-in” strain distribution have been measured and interpreted in terms of phenyl group reorientation and molecular rearrangement, respectively.

In multilayer assemblies consisting of alternating high and low absorption index materials the strongly absorbing (metal) component layer is usually microcrystalline. The crystallite size influences the soft X-ray reflectivity of the stack by determining the effective reflecting area of the stack and the diffuse scattering contribution. The influence of the deposition parameters on the structure of ion-beam sputtered Ni and a-C films is described together with the associated multilayer soft X-ray reflectivity spectra as a function of sputtering energy, d-spacing and film thickness ratio.

Injection moulded plaques of polystyrene and of two types of high density polyethylene have been produced under different moulding conditions. The mean densityϱ of each plaque together with its surface microhardnessVH have been measured. Polystyrene shows only a slight increase inϱ with increasing mould temperatureTm together with a reduced spread inϱ andVH values. In polyethylene, however,ϱ andVH both increase linearly withTm, giving a usefulVH againstϱ relation, which is attributed to increased percentage crystallinity.

The neutron reflectivity spectra of Ni-aimultilayers has been measured as a function of angle of incidence and neutron wavelength in the range 1-7Å. The measurements are discussed in terms of the fabrication method employed and compared with the corresponding X-ray reflectivity spectra.

We here present a new, simple and experimentally unambiguous method of assessing the reflectivity of concave X-ray multilayer mirrors. Preliminary results indicating reflectivities ≈80% of the calculated value are shown for mirrors of 100mm radius of curvature fabricated for use in a 236Å XUV laser scheme.

Plane multilayer mirrors 5 cm in diameter and of different 2-D values have been fabricated from polycrystalline platinum and amorphous carbon. The performance of these multilayers at 0.834-nm wavelength has been measured as a function of layer number and thickness. The importance of the commensurate nature of the stack is described with reference to TEM photographs and resistivity measurements.