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In this work reactive pulsed laser deposition of molybdenum- and tungsten-nitride thin films is investigated. Metallic targets were ablated in low-pressure (1, 10 and 100 Pa) nitrogen atmosphere by KrF excimer laser pulses (fluence ∼6.5 J/cm2). Films were deposited on silicon wafers heated to ∼25, 250 and 500 °C. The characteristics of the films strongly depend on the N2 pressure. By increasing N2 pressure, the nitrogen content increases in the films, which leads to a monotonous increase of the electrical resistivity. Deposition rate decreases at 100 Pa as indicated by Rutherford backscattering spectrometry. At this pressure, hardness of the films significantly decreases also, as shown by microhardness measurements. X-ray diffractometry shows that films crystallinity is improved by increasing the substrate temperature. In addition, atomic force microscopy (AFM) and scanning electron microscopy (SEM) were applied for visualising the film surface.

All the compounds predicted from the SiNi phase diagram were observed by depositing thin layers of nickel onto silicon in known quantities and ratios to each other using an unreactive substrate such as SiO2. After deposition, the samples were annealed in the temperature range 200–750°C and analysed using 2 MeV 4He+ Rutherford backscattering spectrometry and X-ray diffraction techniques. Ni2Si is the first phase formed at a low temperature (about 250°C). Under silicon-rich conditions the system develops in a reproducible manner, subsequently giving rise, when all the nickel has reacted, to the formation of NiSi and of NiSi2 by reaction at 750°C of the NiSi with silicon. The kinetic diffusion approach accounts for the formation and sequence of Ni2Si and NiSi. The phase Ni5Si2 forms between Ni2Si and nickel under nickel-rich conditions. The phases Ni3Si2 and Ni3Si were observed at 400°C and 450°C respectively.

The reaction between molybdenum thin films and single-crystal Si〈111〉 substrates was studied as a function of the concentrations of impurities (mainly oxygen) in the metal film. At a low oxygen concent (1–2 at.%), only the silicide phase MoSi 2 was observed, and a thickness proportional to the square root of time corresponding to an average activation energy of 3 eV in the temperature range 545–600 °C was found. During the formation of the silicide the oxygen originally present in the molybdenum films accumulates at the interface between the silicon and the MoSi 2 . In contrast, a higher oxygen content (4–5 at.%) prevents the formation of any silicide phases in the above temperature range and leads to the formation of MoSi 2 and Mo 5 Si 3 phases at temperatures near 800 °C. MoSi 2 was always observed at the inner interface with Mo 5 Si 3 on the surface. The oxygen segregates from the silicides and accumulates at the Si-MoSi 2 and MoSi 2 -Mo 5 Si 3 interfaces to form a non-uniform layer of SiO x ( x ⩽ 2).

The backscattering technique has been used to study the interdiffusion process of Cr and Au films deposited on silicon substrates. The results indicate that Au diffuses in Cr with an effective diffusion coefficient D = const. exp (−0.68/ k T) . The activation energy is consistent with a diffusion process which occurs preferentially through grain boundaries. The high value of the diffusion coefficient justifies the presence of Au at the CrSi interface after a low temperature short-time heat treatment. At temperatures above 370 °C (the eutectic point of the SiAu system) and after a long enough heat treatment the gold is completely mixed with silicon.

Solid phase processes were used to obtain epitaxial Ge layers 0.1-0.6 μm thick. The structures were formed by evaporating Pd and Ge onto 〈111〉Ge substrates. The samples were initially heated at 250°C to form PdGe and were subsequently heated at about 450°C to obtain Ge growth. They were analysed by MeV He + backscattering and channelling effect measurements (X-ray diffraction was used to verify the stoichiometry of PdGe). The Pd profile in the grown Ge layer was determined. Channelling measurements showed that the grown Ge layers were well ordered and epitaxial with the underlying substrate.

The following platinum X-ray absorption edges were measured in platinum silicides: Pt2Si L2,3, PtSi L2,3 and PtSi M2,3. The results are compared with the edges measured in platinum metal. As well as the known peak at the edges of index 3, a new strong peak absent in the metal appears at the edges of index 2 of the silicides. This effect is very strong in the M2 edge in spite of the linewidth which is greater than that in L2. The results are interpreted in terms of transitions to empty d states typical of the hybridization (Si p)-(Pt d) which gives rise to states with projections onto j= 3 2 and j= 5 2 so that the peak due to p-d transitions is present in the edges of index 2 and of index 3. The different localization involved in M and L transitions is also discussed.

In this communication reflectance and thermoreflectance spectra of films of PtSi and Pt 2 Si grown on glass substrates are reported and discussed. Weak structures superimposed on the free-carrier response of the reflectance spectra are detected by means of thermoreflectance. Attributions of such structures mainly in terms of d-d transitions are briefly discussed.

We investigated the rate of germanide formation and the composition of the resulting compounds when thin (1000–2500 A) palladium films, vacuum evaporated onto various germanium substrates, were annealed at temperatures from 170 to 270°C for 10 min to 27 h. Both phases, Pd2Ge and PdGe, were observed on single-crystal and amorphous (vacuum-deposited) germanium substrates. In all cases the compounds layers grow with a (time) 1 2 dependence and with an activation energy of 1.5 ± 0.1 eV. Moreover the absolute value of the growth rate depends on the crystalline nature of the germanium substrate. On (111) and (100) substrates the rates are similar and they are three times lower than those on amorphous substrates.