Two doses (1013 and 1015 cm−2) of tungsten (W) atoms were implanted in different Si(001) wafers in order to study W diffusion in Si. The samples were annealed or oxidized at temperatures between 776 and 960 °C. The diffusion profiles were measured by secondary ion mass spectrometry, and defect formation was studied by transmission electron microscopy and atom probe tomography. W is shown to reduce Si recrystallization after implantation and to exhibit, in the temperature range investigated, a solubility limit close to 0.15%–0.2%, which is higher than the solubility limit of usual metallic impurities in Si. W diffusion exhibits unusual linear diffusion profiles with a maximum concentration always located at the Si surface, slower kinetics than other metals in Si, and promotes vacancy accumulation close to the Si surface, with the formation of hollow cavities in the case of the higher W dose. In addition, Si self-interstitial injection during oxidation is shown to promote W-Si clustering. Taking into account these observations, a diffusion model based on the simultaneous diffusion of interstitial W atoms and W-Si atomic pairs is proposed since usual models used to model diffusion of metallic impurities and dopants in Si cannot reproduce experimental observations.

Well-controlled population of dislocations are introduced in 4H-SiC by bending in cantilever mode and annealing between 400 and 700°C. The introduced defects consist of double stacking faults, each bound by a pair of 30° Si(g) partial dislocations, and the expansion of which is asymmetric. The velocity of each individual 30° Si(g) pair is directly measured as a function of stress and temperature on the surface of samples etched after deformation. The activation energies of the 30° Si(g) partial dislocation pairs are strongly stress dependent, ranging between 1.25 and 1.7eV. These values are lower than the ones derived from plasticity experiments. This is probably because 30° Si(g) pairs and double stacking faults are generated in N-doped 4H-SiC (N=2×1018cm−3), with their development being promoted by quantum well action.

Thermally induced transition metal contamination of silicide Schottky barriers on silicon AIP Conf.The solid state reaction between a Ni ͑7 at. % Au͒ film and a Si substrate at temperatures ranging from 250 to 800°C is examined by scanning electron microscopy, x-ray diffraction, and Rutherford backscattering spectrometry. Compared to the usual features for thin film reaction of Ni with Si, we observed the following. ͑i͒ The simultaneous growth of Ni 2 Si and NiSi, and the growth of NiSi at the expense of both Ni 2 Si and Ni. This is related to Au accumulation in the metal layer. ͑ii͒ Au precipitation at 300°C followed by the dissolution of the clusters thus created above the Au-Si eutectic temperature ͑370°C͒. ͑iii͒ A decrease of the temperature of formation of NiSi 2 and the appearance of thickness oscillations that are characteristic of nucleation. These different effects are interpreted by taking into account the metallurgy of the system: segregation of Au in the Ni film, Au solubility in the different silicides, change in surface and interface energies, and chemical interactions with Si.