C.A. Olivieri

Distributions of light ions and foil destruction after irradiation of organic polymers

It is found that light ions (6Li, 10B) distribute neither according to their calculated range nor to their nuclear damage distributions but according to their ionization distributions after implantation into organic polymers. Also, the profile of chemical destruction after low dose light ion implantation (typically 1012–1014 ions/cm2) into organic foils obeys the ionization distribution rather than the range or nuclear damage distributions. After annealing, or at higher implanted doses, a slight shift of the implantation or destruction profiles towards the nuclear damage distribution is found. The reason for this implantation behavior may be partly understood in terms of diffusion and subsequent recombination with the created radicals. Li and B distributions in carbon (which may be regarded as the final product of polymer destruction) show a shape which can be described by range profiles with subsequent diffusion and trapping at homogeneously distributed defects. In contrast to light ions, implanted heavy...

Range profiles of implanted Bi and Au in amorphous silicon

Abstract The Rutherford backscattering technique is used to measure the depth profiles for 10 to 390 keV 209Bi and 15 to 390 keV 197Au implanted in amorphized silicon wafers. The obtained projected ranges and projected range stragglings are compared with previous data and with recent universal range-energy calculations. Whereas good agreement is found between the experimental and theoretical range predictions for Bi, the measurements for Au yield, at low energies, ranges longer than predicted. The discrepancy between measured Au and Bi ranges is ascribed to the Z1-range oscillation.

Range profiles of 10 to 390 keV ions (29 ≦ Z1 ≦ 83) implanted into amorphous silicon☆

Abstract Our recent range profile measurements for a series of elements (29 ≦ Z1 ≦ 83) implanted from 10 to 390 keV in amorphous silicon are compared with the Biersack-Ziegler (BZ) calculations. While the theoretical predictions are in good agreement with the experimental ranges at implantation energies larger than 70 keV, the results for several elements at lower energies are strongly underestimated by the calculations. These differences are ascribed to the Z1-range oscillation effect. In the present work we perform range calculations simulating a decrease of the elastic interaction at low energies. This approach is phenomenologically related to modifications of the charge distribution during the collisions. The results obtained show a better agreement between the calculations and the great majority of the existing low energy experimental ranges in silicon substrates.

Energy dependence of the Z1-range oscillation effect in silicon

Abstract Precise measurements of projected ranges for several ionic species implanted into amorphous silicon at energies from 10 to 380 keV are compared with the new theoretical predictions of Biersack and Ziegler. For Ga, Br, Rb, Pd, Sn and Bi ions, the experimental and calculated ranges agree within ± 10% or better. In the cases of Eu, Yb and Au however, large deviations, up to 60%, were observed at very low energies. These “Z1-oscillations” were found to diminish with increasing energies and disappeared around 100 keV.

Range Profiles of 10 to 380 keV 120Sn and 133Cs in amorphous silicon

Abstract Depth profiles of 120Sn and 133Cs implanted at energies from 10 to 380 keV in amorphized silicon wafers are measured by 4He ion Rutherford backscattering. The obtained projected ranges and projected range stragglings are compared with previous results and with recent universal range-energy calculations. The data for the Sn-Cs pair are also analysed in terms of the Z1-range oscillation effect.

Range profiles of ions in double-layer structures

Abstract By means of (n, p) or (n, α) spectrometry some concentration distributions of 3He. 6Li, and 10B implanted into metallic and/or semiconducting double-layer structures are measured. The samples are characterised by RBS. In many cases good agreement with theory is achieved. Sometimes, the implanted ions show enhanced mobility during the implantation into the multilayer structures, even if this is not the case for implantation into the homogeneous targets of the same materials. This enhanced mobility is indicated by the additional occurrence of precipitations at the interface and surface, and by changes in the shape of the profiles.

Large Z1-range effect for Eu, Yb and Au ions implanted in amorphized silicon

Abstract The Z1-range oscillation amplitude is investigated as a function of energy for Eu, Yb and Au ions implanted in amorphous Si at energies from 10 to 390 keV. The obtained experimental results are not reproduced by the recent theoretical predictions of Burenkov and collaborators, showing large discrepancies for energies lower than 50 keV.

Range and range straggling of 15 to 350 keV 69Ga in amorphous silicon

Abstract Depth distribution profiles of 15 to 350 keV 69Ga+ implanted at room temperature in amorphized silicon have been measured by 4He ion Rutherford backscattering. The measured projected ranges and range stragglings are in excellent agreement with the predictions calculated via realistic Monte Carlo simulations, TRIM code.

Range distributions and thermal behaviour of Bi implanted into kcl and Al/KCl bilayer structures

Abstract 300 keV Bi + was implanted into an Al(610 A)/KCl bilayer structure, and for comparison into a pure KCl single crystal. The Bi depth distribution, measured by RBS, agrees well with theoretical predictions (TRIM) in both cases. Thermal annealing yields two stages: first, up to 200°C, the Bi distribution changes rapidly, probably due to diffusion enhanced by radiation damage in KCl. At higher temperatures, those defects anneal out, so that essentially regular diffusion governs the depth profiles up to 500°C, and an Arrhenius diagram can be given. For the Al/KCl bilayer structure, we find retarded diffusion in a rather broad interval around the interface, in agreement with previous findings for Bi in the Al/Ti bilayer structure.

Depth profile and thermal annealing behavior of Bi implanted into an Al/Ti bilayer structure

600‐keV Bi was implanted into an Al/Ti bilayer structure. There is good agreement between the Bi depth profile measured by Rutherford backscattering and corresponding theoretical prediction (Monte Carlo code trim). After annealing at low temperatures, the pronounced structure of Bi concentration at the Al/Ti interface vanishes, and the buildup of a surface precipitation is observed. At 500 °C annealing, strong Bi diffusion sets in, associated with the intermixing of the substrate components. A thin oxide layer present at the surface acts as a diffusion barrier for Bi, resulting in Bi segregation at the oxide/alloy interface.