[en] In order to provide engineering power devices with a good thermal stabilization of the lifetime with the temperature, we performed a proton implantation following by a helium one. The process resulted in a drastic improvement of the power rectifier parameters particularly a better stabilization versus temperature. While a lifetime control performed by gold or platinum resulted in a variation of lifetime by a factor of about 2 when the temperature increases from 25 to 125 deg. C, diodes processed with co-implantation gave a factor of about 1.4

[en] Cavities were created by MeV He implantation in silicon through a 1.5 μm Al foil. After a 800 deg. C-annealing, unexpected growth mechanism was found: a non-uniform layer of cavities with a distribution where bigger cavities are surrounded by smaller ones. Neither Oswald ripening nor migration-coalescence mechanisms can be applied to describe the growth of these cavities. The role of dislocations seem to be important in that distribution. Indeed some cavities seem to be trapped by dislocations. However the motion of the helium does not appear to be the origin of that anormal growth mechanism

[en] Different levels of damage were first introduced into CZ p-type Si (100) by the implantation of 80 keV Si ions to different doses ranging from 10¹⁴ to 5x10¹⁵ cm^-2. All the Si implanted samples together with virgin Si were then subjected to 1 MeV ³He ion implantation to the same dose of 5x10¹⁶ cm^-2. Cross-sectional transmission electron microscopy (XTEM) and nuclear reaction analysis (NRA) measurements were used to quantify the evolution of He-cavities and He desorption from the cavities after subsequent annealing, respectively. Our results show that the presence of high level of damage induced by Si implants tends to inhibit the growth of He-cavities and increase the rate of He desorption. The results are tentatively interpreted on the basis of the evolution of Si induced damage upon annealing and its interaction with He-cavities

[en] Si(1 0 0) samples of n-type have been implanted with 5.6 MeV ²⁸Si³⁺ at room temperature using a dose of 1x10⁸ cm^-2. Thereafter the samples were annealed in nitrogen ambient for 30 min at temperatures from 400 deg. C to 800 deg. C using steps of 50 deg. C. Deep level transient spectroscopy (DLTS) was used for sample analysis. Deep levels, not previously reported in the literature, are observed to arise, evolve, and to vanish again in the described temperature interval, while above 650 deg. C only two defects levels remain. Depth profiles of these levels show, that the maximum concentrations of the defects are located deeper than the projected range, as is characteristic for secondary implantation defects. Their possible identities are discussed

[en] Crystalline silicon samples were first implanted at room temperature with 160 keV He ions at a dose of 5 x 10¹⁶ ions/cm². Some of these samples were then co-implanted with 80 keV Si ions to a dose of 5 x 10¹⁵ ions/cm², or were co-treated with high density hydrogen plasma. Cross-sectional transmission electronic microscopy (XTEM) was used to study the growth of cavities after the subsequent annealing at 800 degree C for 1 hour. The results clearly show that both the Si implant and plasma hydrogenation can influence the growth of cavities in Si. In Si ion co-implanted sample, the cavities were found to shrink due to the presentation of excess of interstitial-like defects. However, additional plasma hydrogenation leads to enhancement in cavity growth. The results were qualitatively discussed. (author)

[en] Crystalline silicon samples were implanted at room temperature with 1.55 MeV ³He ions at different doses ranging from 5 x 10¹⁵ to 5 x 10¹⁶/cm². Damage production after subsequent high temperature annealing was studied by using cross-sectional transmission electron microscopy (XTEM). Meanwhile, nuclear reaction analysis (NRA) was used to study the behavior of ³He desorption from the implanted samples. Our results show that at low dose range, the He implantation followed by high temperature annealing only induces the creation of small dislocations, and at intermediate dose range, clusters of bubbles accompanied with high density of dislocation loops were observed, while for the higher implanted dose, a well defined cavity band was formed at the depth corresponding to the projected ³He range. The phenomena were discussed in combination with NRA results. (authors)

[en] Due to recent progress in silicon carbide (SiC) technology, understanding the behaviour of defects in SiC is a crucial challenge for the industrial development of SiC-based devices. High energy helium ion implantation at high fluence in SiC creates a few microns deep damaged layers with nanocavities which are expected to play an important role in gettering of unwanted impurities. Post-implantation evolution of the ion implantation-induced damage is then controlled by thermal annealing. Results of an infrared reflectivity (IRR) and X-ray diffraction (XRD) study of ion implantation-induced damage in crystalline (0 0 0 1) n-type 4H-SiC implanted at room temperature with 1.6 MeV He⁺ ions at the fluence of 10¹⁷ cm^-2 show the formation of two layers above the unperturbed crystal: a 3.4 μm deep defective strained surface layer on a 0.4 μm thick strongly perturbed interface layer. Thermal annealing at 1500 deg. C for 30 min under high vacuum was shown to induce structural recovery of the surface layer

[en] Epitaxial silicon samples of n-type have been implanted with 850 keV protons at a dose of 5x10¹³H⁺ cm^-2. Subsequent in-diffusion of platinum at 700 deg. C for 30 min resulted in the presence of a single deep level, which is attributed to the platinum acceptor level, at 0.23 eV below the conduction band edge. Depth profiling of this level shows that the substitutional platinum is following the vacancy profile in the peak region around the projected range for the protons. In addition, at more shallow depths, a strong increase of the platinum concentration is also observed. Without ion-implantation, no deep levels are detected after in-diffusion at 700 deg. C, while at 800 deg. C, the Pt deep level concentration is inferior to the one reached after pre-implantation with the above dose. After in-diffusion at 600 deg. C into the implanted sample, many defects are observed. One of these is the substitutional platinum, while the others are considered to be of interstitial nature, due to the fact that their maximum concentration is found to be deeper than the projected range of the irradiation. The role of these latter defects in the process of platinum proximity gettering is discussed

[en] In this work, we produced thin silicon layers by means of hydrogen implantation. We used 650 keV, 1.0 MeV, 1.5 MeV and 2.0 MeV hydrogen for layer thicknesses of about 9, 16, 30 and 48 μm according to TRIM simulations. The critical dose was found to be 5 x 10¹⁶ H⁺/cm² for the first three energies while the highest energy required a higher dose: between 5 x 10¹⁶ and 8 x 10¹⁶ H⁺/cm². Annealing at 600 deg. C in nitrogen atmosphere result in the effective transfer with the expected thickness. High quality Si layers are achieved

[en] The electrical properties of semiconductor components can be greatly modified by proton implantation. Spreading resistance, C-V (capacitance voltage) and DLTS (deep levels transient spectroscopy) measurements have been used to characterize N-type silicon irradiated by MeV proton at fluences up to 10¹⁴p⁺cm^-2. The greatest drawback induced by proton implantation is the overdoping effect which can strongly reduce device efficiency. The present work reports this effect in both annealed and unannealed samples