P. Hendrickx

Implantation temperature dependent distribution of NiSi2 formed by ion beam synthesis in silicon

The formation and distribution of NiSi2 in (111) silicon by Ni‐ion implantation with a fluence of 1.1×1017 cm−2 and an energy of 90 keV is studied as a function of the temperature during implantation. For temperatures below 200 °C, a buried layer of NiSi2 precipitates is formed. Increasing the temperature gradually from 200 to 350 °C leads first to the formation of a double buried NiSi2 layer which with increasing temperature evolves into an epitaxial NiSi2 surface layer. A tentative model to explain for the observed anomalous behavior is presented.

Simultaneous synthesis of well-separated buried and surface silicides using a single ion implantation step

An unusual Ni distribution with two completely separated buried and surface silicide layers has been observed after Ni ion implantation in Si(111) kept at a temperature of 300 °C, with a dose of 1.1×1017/cm2 and at a fixed energy of 90 keV. RBS/channeling, AES, and cross‐sectional TEM have been used to study this phenomenon as a function of the substrate temperature and Co co‐implantation. A model is presented, based on the diffusion of the transition metal, the defect annealing during the implantation, and the gettering power of the surface and the end of range defects.

Pressure effects of krypton bubbles on the host aluminium lattice as probed by 57Co impurity atoms

Abstract Metal lattices containing highly pressurized solid rare gas bubbles are strained under pressure. We have studied these internal pressures by performing Mossbauer measurements on implanted 57 Co probe atoms as a function of annealing temperature. We thus identified two sites: a substitutional site and a “new” site. The behaviour of the isomer shift and recoilless fraction of substitutional cobalt indicated a high compression of the aluminium lattice, which reached a pressure of 77 kbar after annealing to 500 K. At 750 K the system started to relax.

X-ray diffraction, Rutherford backscattering and channeling measurements on Pb inclusions in Si

Pb inclusions have been formed in Si 〈111〉 single crystals by ion implantation to doses of 1015, 5 × 1015 and 1016 at./cm2. Combining Rutherford backscattering spectrometry (RBS), channeling and X-ray diffraction (XRD) results, we obtain information about the pressure in the inclusions, their epitaxy to the host lattice and the dependence of these properties on implantation dose and annealing temperature.

Tetramethyl tin in frozen rare gases. A study of impurity-host binding

Abstract The Mossbauer effect in 119 Sn was applied to obtain information on the local dynamical properties in frozen rare gases. The results show a hardening of th phonon spectrum for the matrix isolated tetramethyl tin molecule in neon and argon. No such enhancement is observed for the matrices of solid krypton and xenon. An explanation based on geometrical considerations is proposed.

133Xe Mössbauer Study of Neon Inclusions in Molybdenum

Mossbauer studies using microscopic local probes like 133Xe and 83Kr have been undertaken to elucidate the nature and growth of very small inclusions. Besides a small fraction of the probe atoms that reside on substitutional sites—we try to reduce this fraction as much as possible—probe atoms are found inside the bubbles and at interface positions. The inside probes, through the measurement of the ~ Debye temperature, allow us to draw conclusions on the specific volume and, with the EOS on the local pressure. The interface probes give us an idea on the mismatch and the local order. A combination of both fractions allows us to deduce the mean size of the inclusions. XRD measurements have been started to complement the Mossbauer based information. Results on Ne, Kr, Xe and Cs will be presented.

Channeling detection using position sensitive detectors

Abstract A channeling detection method based on the simultaneous measurement of several angular scans through the use of a position sensitive detector is presented. With respect to conventional channeling, it is both time saving and much more visual.

Study of the formation of Cs inclusions in refractory bcc metals by133Xe(Cs) Mössbauer resonance

The formation and properties of Cs inclusions in Mo and W are observed through a preimplanted133Xe(Cs) local probe, which is found to reside in three sites: a substitutional site, an interfacial one and a further site which is not detectable directly, but the presence of which can be inferred from the Mössbauer measurements. The location of the probe at the interface of small Cs inclusions is characterized by large Debye temperatures of around 200 K, a quadrupole interaction of +1.86(15) mms−1, which is close to known surface site values, and an isomer shift of −0.33(12) mms−1. From the latter value an approximate local pressure of 5 GPa is deduced. In W the site populations are followed as a function of Cs dose. The observed interchange of populations in the low dose range is thought to represent the initial formation of the second phase inclusions.

FORMATION OF WELL-SEPARATED BURIED AND SURFACE NICKEL-SILICIDE LAYERS IN A SINGLE ION IMPLANTATION STEP

An unusual Ni distribution with two completely separated buried and surface silicide layers has been observed after Ni ion implantation in Si(111) kept at a temperature of 300 C, with a dose of 1.1 x 1017/cm2 and at a fixed energy of 90 keV. RBS/channeling, AES and cross-sectional TEM have been used to study this phenomenon as a function of the substrate temperature and Co co-implantation. A model is presented, based on the diffusion of the transition metal, the defect annealing during the implantation, and the gettering power of the surface and the end of range defects.