A tomic mixing resulting from heavy-ion bombardment of thin-film Ni/Pd bilayers and thin Pd markers sandwiched between Ni layers has been investigated. Mixing experiments were performed over a temperature range 40–473 K, using 120 keV Ar+ and 145 keV Kr+ ions at a constant dose rate of 5.5 × 1012 ions cm −2s−1 for doses up to 4 × 1016cm−2. The resulting interdiffusion was measured, in situ, using Rutherford backscattering with 2−2.8 MeV 4He+ ions. The results showed that, for both markers and bilayers, the amount of mixing is similar for both configurations and varies linearly with the square root of the ion dose. Comparison of the induced mixing per ion, following irradiation at 40 K, shows that the mixing is dependent on the damage energy FD deposited at the interface region. The mixing is essentially athermal.

Atomic mixing in Ni/Pd bilayer films due to 120 keV Ar+ irradiation in the thermally assisted regime (523−673 K) has been measured, in situ, using Rutherford backscattering with 2.0 MeV 4He+ ions. The mean diameter of grains in these polycrystallinc films increased from 10 to 60 nm, following Ar+ bombardment at 573 K. Initial mixing was rapid due to grain boundary diffusion and incorporation of the metal solute into the solvent metal matrix by grain growth; this mixing stage was essentially complete within 10 min for annealed films or after an Ar+ dose of 4 × 1015 cm−2 in irradiated films (10 min irradiation). No further measurable mixing occurred in the annealed, unirradiated films. For the irradiated samples the initial rapid mixing (6−35 atoms/ion) was followed by a slower mixing stage of 0.7–1.8 atoms/ion for irradiation doses of up to 2.5 × 1016 Ar+ cm−2. The Ar+ bombardment gave rise to much smaller mixing levels when the Pd films were deposited on large-grain or single-crystal Ni. A diffusion analysis demonstrates that the effective diffusivity, Deff, for ion-irradiation-enhanced mixing in the thermally assisted regime satisfied the relation Dl < Deff < DB, where the ratio of the grain boundary to lattice diffusivity was DB/Dl > 106.

Parametric experiments are described that characterize the process of atomic relocation in Ni/SiO2 bilayers induced by Xe irradiation. The parameters varied are the irradiation temperature (− 196 to + 500 °C) and the Xe irradiation dose (0.01−15 × 1015cm−2). Backscattering spectrometry of the irradiated samples after removal of the unreacted Ni film is the main analytical tool. A phenomenological model is given that describes the results quantitatively. It is deduced that secondary recoil implantation followed by subsequent redistribution within the cascade's lifetime produces the dominant transport mechanism responsible for incorporating Ni into the SiO2.

Ion-beam mixing and thermal annealing of thin, alternating layers of Al and Nb, as well as Al and Ta, were investigated by selected area diffraction and Rutherford backscattcring. The individual layer thicknesses were adjusted to obtain the overall compositions as Al3Nb and Al3Ta. The films were ion mixed with 1 MeV Au+ ions at a dose of 1 × 1016 ions cm−2. Uniform mixing and amorphization were achieved for both Al−Nb and Al−Ta systems. Equilibrium crystalline A13Nb and Al13Ta phases were formed after annealing of ion mixed amorphous films at 400 °C for 1 h. Unmixed films, however, remained unreacted at 400 °C for 1 h. Partial reaction was observed in the unmixed film of Al–Nb at 400 °C for 6 h. After annealing at 500 °C for 1 h, a complete reaction and formation of Al3Nb and Al3Ta phases in the respective films were observed. The influence of thermodynamics on the phase formation by ion mixing and thermal annealing is discussed.

The grazing x-ray reflectrometry technique was used as a way to study modifications in metallic multilayers induced by ion-beam irradiation. Due to the high sensitivity of the technique, short-range atomic displacements of an atom A in a layer B can be detected so that the first stages of ion-beam mixing can be investigated. The rate of mixing is measured and the compound A1−xBx formed at the layers' interfaces is characterized.

The (0001), (1010), and (2110) faces of Bi have been pulsed laser irradiated at 0.5–0.8 J/cm2 with a Q-switched ruby laser. Nomarski interference contrast microscopy, channeling, and selective chemical etching have been used to investigate the response of the material to the laser irradiation. The response of Bi is shown to be strongly orientation dependent. The χmin and half-angle for the Bi (0001) surface have been measured and compared to theoretical values. The Bi(0001) surface has been shown to regrow epitaxially without an increase in the disorder. In contrast, the epitaxial regrowth of the Bi(1010) and Bi(2110) surfaces show a marked increase in disorder after irradiation. The levels of damage show a strong correlation to the critical resolved shear stress characteristics in the particular crystallographic orientation studied.

Dry sliding friction measurements made on titanium layers evaporated on AISI 304 stainless steel in the as-deposited and excimer laser mixed form show a dependence on the film thickness and the amount of mixing. The effect of laser mixing is dependent on the incident fluence with high fluences and/or large numbers of pulses producing surfaces with poor frictional properties. The optimum total fluence depends on the thickness of the surface layer, a result consistent with thorough mixing of the alloyed layer without the surface damage that results from large numbers of pulses.

The effect of the parameters of laser irradiation (beam power and travel velocity) as well as of various surface coatings and protecting atmospheres on the size, structure, and hardness of the laser-affected region was studied in the case of commercial 1045 steel and a continuous CO2 laser. The action of the laser beam depends more strongly on its traverse velocity than on its power. When the power density exceeds a certain threshold level, a drastic decrease in the size of the laser-affected region takes place. The action can be enhanced by surface treatment in orthophosphoric acid as well as by some painted surface coatings. Unlike the latter, electroplated Cr and Ni layers were found to cause substantial alloying of the laser-treated layer. The laser-affected region formed by a single pass consists of two distinct zones: a melt zone, surrounded by an austenitization zone with a duplex structure representing former pearlite and ferrite regions. The hardness of the melt zone (about HV 750) exceeds that of conventionally hardened 1045 steel; even higher values (up to HV 900) are observed in the former pearlite regions of the austeniti zation zone, that of the former ferrite regions being about HV 250. In the case of an extended surface processed by a series of equidistant passes, a relatively wide region of tempered martensite is formed (with minimum hardness values down to HV 400) due to the heating generated by each pass in the previously hardened layer. As a result, a periodic hardness distribution is observed, whose fcatures depend on the degree of overlapping. High tensile residual stresses were found by x-ray diffraction in surface layers both in the cases of overlapping and separated passes.

Pulsed excimer laser radiation has been successfully employed in the improvement (> 50%) of fracture strength of metal-coated ceramics. Thin metallic layers (∼500 Å) of nickel were deposited on silicon nitride and silicon carbide substrates and further irradiated with pulsed excimer (xenon chloride, krypton fluoride) laser pulses. The laser energy density was varied from 0.4 to 2.0 J cm −2 to optimize the formation of mixed interfacial layers. The formation of interfacial layers was studied by transmission electron microscopy and Rutherford backscattering spectrometry techniques. Detailed heat flow calculations using implicit finite difference methods were performed to simulate the effects of intense laser irradiation on metal-coated ceramic structures. Three different mechanisms were found to play an important role in the improvement in the fracture strength of these ceramics. Theoretical calculations showed that the displacement of the crack tip away from the free surface by laser surface modification can lead to a 100% improvement in the fracture strength of the ceramic.

Bulk polycrystalline samples of sintered Al2O3, and hot-pressed Al2O3, SiC, TiB2, and B4C ceramics were ion implanted at 77 K with 190 keV N+ to a dose of 3 × 1017 N/cm2. Nitrogen implantation resulted in reduced friction coefficients for SiC, TiB2, and B4C samples and a reduction in wear for TiB2. Both Al2O3 samples showed a significant increase in friction coefficients after nitrogen implantation. Nitrogen-implantation-induced changes in these properties appear to be correlated with the thermodynamic tendency of the sample to form “nitridelike” bonds.

Steel (AISI-304) disks, polished to a 3 μm diamond finish, were implanted to doses of about 2 × 1017/cm2 with N+, Ni+ or, Ne+, ions. Polishing wear rates, measured to a depth resolution of about 20 nm, showed that each of the implanted disks wore 20% to 40% faster than nonimplanted layers. Auger analysis showed (1) Gaussian-like profiles of the N-implanted layer, but with somewhat enhanced oxidation of the surface, and (2) a sputter-limited implantation profile in the Ni-implantcd layer, with some vacuum carburization. Transmission electron microscope analysis indicated that polishing produced an α′-martensite layer in the mainly austenitic 304 surface, but that implantation of N transformed the martensite to austenite at the outermost layers and produced iron nitrides below. In addition. Nimplantation stabilized the austenite against martensite transformation during subsequent wear. Martensite vanished after Ni implantation because of sputter removal, not phase transformation, during Ni bombardment. The Ne-implanted layer remained predominantly martensite. Changes in wear rates and microstructures were confined to depths commensurate with the range of ions in the implanted layer. Several hypotheses on the effects of ion implantation on microstructureand wear are discussed.

Ultraviolet photon-induced metalorganic vapor phase epitaxy of CdTe films on GaAs substrates has been investigated using diethyltelluride and dimethylcadmium as the precursor gases. The relationship between the deposition parameters and the properties of the epilayers have been examined using transmission electron microscopy and x-ray rocking curves. Epilayers grown at 6μm/h show an x-ray double-crystal rocking curve full width at half-maximum (FWHM) of 250 arcsec.

Thin films of aluminum oxide and titanium dioxide have been deposited onto gallium arsenide at low temperatures (<200 °C). A high-pressure xenon–mercury are lamp (1 kW) and a frequency doubled argon ion laser (100 mW at 257 nm) have been used as illumination sources Suitable volatile metallo-organic precursors have been synthesized with strong absorptions at the wavelengths of the light sources. The Al2O3 or TiO2 layers grown at 200 °C or less are amorphous although the anatase phase of TiO2 is deposited at temperatures over 350 °C. Ellipsometry has been used to measure the thickness and refractive index of the films. Films have been deposited onto gold on silicon in order to make simple electrical measurements. Resistivity, dielectric constant, loss factor, and breakdown voltage have been measured. The results shows values in good agreement with the results published on films grown by other CVD techniques using much higher temperatures.

A versatile, repetitively pulsed source of translationally fast, reactive molecules is described that is suitable for materials processing experiments. The pulsed beams are generated by excimer laser vaporization of cryogenic molecular films that are continuously condensed on transparent substrates. The generation of fast, energy variable pulsed molecular sources of Cl2 and NO is demonstrated. The most probable translational energies of Cl2 and NO molecules can be reproducibly varied monotonically by adjusting the laser fluence or film thickness. Here, the most probable translational energy is quoted as the energy corresponding to the maximum of the time-of-flight trace. Using laser fluences of 2–25 mJ cm−2 from a 193 nm excimer laser, the most probable translational energies of Cl2 are 0.4–2 eV. Significant fractions of molecules with translational energies greater than 3 eV are observed at the leading edges of the distributions. Very similar results are obtained by vaporizing Cl2 with 248 and 351 nm radiation. Pulses of translationally fast NO molecules are generated in a similar manner; most probable energies from 0.1–0.4 eV, with the fastest molecules up to 0.8 eV, are obtained using laser fluences of 1–11 mJ cm−2 at 193 nm. Approximately 1013−1014 molecules per cm2 of the film are vaporized per laser pulse, depending on film thickness and laser fluence.

Thin films of Ho1Ba2Cu3O7 − x and Y1Ba2Cu3O7 − x were deposited on SrTiO3 and Al2O3, substrates by pulsed laser deposition of high-Tc bulk superconductor pellets in vacuum. Following annealing in O2 at 800–900 °C the films were superconducting with typical Tc (50%) = 89 K and transition widths of 10 K. Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) were utilized to study the stoichiometry of the as-deposited films for laser energy, densities between 0.11 and 4.5 J cm−2. The films were deficient in holmium and yttrium for energy densities below 0.6 and 0.4 J cm −2, respectively. The films were stoichiometric for fluences above 0.6 J cm−2. In addition, preliminary time dependence and spectroscopic observations of the laser-produced plasma are presented. The results indicate an ablation mechanism that at high energy densities preserves stoichiometry. TEM and x-ray characterization of annealed, superconducting Ho1Ba2Cu3O7 − x films on (100) SrTiO3 showed mixed regions of epitaxially oriented 1:2:3 material with either the c axis or a axis oriented along the surface normal. The a-axis-oriented material grew preferentially in the films with b, c, twinning.

Thin films of SnO2−x (0<x<1) were deposited on Corning glass and alumina substrates by employing a pulsed laser evaporation (PLE) technique. The microstructural features of the films were probed with Sn119 conversion electron Mössbaucr spectroscopy (CEMS) whereas the structural characteristics were identified by using low-angle x-ray diffraction measurements. The electrical and optical properties have also been studied. It is shown that films with conductivity of 3 × 102 (ohm·cm)−1 and transmission of 90% can be obtained by appropriate postannealing of the as-deposited films in air and vacuum. The energy gap of this nearly stoichiometric single-phase SnO2 film was found to be 3.5 eV and spectroscopic ellipsometry measurements indicated the refractive index lobe typically between 1.8–1.9 over the wavelength range of 400–800 nm.

Some observations of laser marking of thin films are presented. Time-resolved reflectivity measurements performed during laser marking of thin organic films indicate that the pit-formation processes start in less than 10 ns after the onset of the laser pulse and that some reversal of the process occurs following exposure termination. Temperature calculations for laser heating of thin films with focused scanning beams explain some of the mark (pit) morphology and material flow behavior that is observed. Scanning electron microscopy (SEM) studies of the marks indicate that at high laser powers, pit formation occurs by ablation and at low laser powers, pits can be formed without ablation. Pits were also formed in a 100nm thin film by resistive heating where the maximum temperature was less than 300 °C.

The crystallization kinetics of thin (35 and 60 nm) amorphous as-deposited Ge films were studied using diffraction limited laser beam irradiation and laser pulses between 30 ns and 1 ms. The recrystallization of crystalline as-deposited films was also studied for similar laser conditions. Crystallization was observed for pulses as short as 50 ns. It was concluded that the irradiation of amorphous thin films with small beam spots (∼ 1μm) gives a very different crystallization morphology from that observed previously for larger beam diameter and same laser pulse length. In the present case for short irradiation times, the nucleation process dominates over crystal growth. Temperature calculations allow the understanding of these results by showing that only the small spot irradiation sustains the material at high temperature for times comparable to the pulse width. Laser irradiation of as-deposited crystalline films produced grains with significantly fewer defects than grains crystallized from as-deposited amorphous films.

Different Raman experiments on structural relaxation of a-Si and a-Ge are reviewed and discussed in relation to calorimetric measurements on a-Ge. On the basis of the correlation found between results from Raman spectroscopy and results from calorimetry in the case of a-Ge and of the strong similarity between a-Si and a-Ge in terms of their Raman spectra, it is suggested that the strain energy in a-Si may vary considerably with preparation conditions and subsequent treatments. Under this assumption the a-Si Gibbs free energy versus temperature has been constructed for material in different initial states of relaxation. It is shown that the melting temperature of amorphous silicon should increase when relaxation occurs during the heating phase prior to melting. Thus differences in apparent melting temperature, as observed under different laser heating conditions, may be explained.

The ion-bombardment-induced reversible movement of a planar amorphous/crystalline interface in silicon has been studied between 100 and 400 °C. The temperature dependence of the ion dose rate at which there is zero interface movement has an activation energy of 1.2 eV, the dissociation energy of divacancies. Scaling of this dose rate for different ion species exhibits a quadratic dependence on the density of displaced atoms in the collision cascade of individual ions, giving further evidence for divacancy control of the interface movement.