The creation of defects by hydrogen in silver-doped silicon crystals is investigated by deep-level transient spectroscopy. The electrical activity of the substitutional silver impurities can be totally removed due to defect formation with hydrogen atoms. However, this process includes the creation of intermediate electrically active silver-hydrogen complexes. One of the defects, Ag-H 1 , contains one hydrogen atom and introduces three levels in the energy gap. Another electrically active complex is formed by addition of a second hydrogen atom to the Ag-H 1 defect. The Ag-H complexes are stable up to 300-350°C. The electrically inactive complex includes at least three hydrogen atoms and anneals out at ϳ450°C. The kinetics of the defect transformations are studied in detail, and the distance of silver-hydrogen interaction is estimated to be very close to the lattice parameter. ͓S0163-1829͑99͒02308-5͔

The effect of wet chemical etching in acid solutions on the energy spectrum of n-and p-type silicon crystals previously irradiated with high-energy electrons is studied by deep-level transient spectroscopy. It is observed that together with the well known radiation defects a number of novel deep-level centres appear near the etched surface. The depth profiles of the deep-level centres are investigated depending on the irradiation dose and the temperature of subsequent annealing. The novel centres observed are shown to be complexes of radiation defects with the hydrogen atoms which penetrated into the crystal during etching. The origin of some of these centres from the particular vacancy-related defects is established. A simple quantitative description is given of hydrogen atom penetration during the etching and formation of the hydrogen-radiation defect complexes. Based on this analysis, the radius of hydrogen capture to the well known A-centre (vacancy-oxygen complex) is estimated and the centre with an energy level of E c − 0.32 eV is identified as a complex of the A-centre with two hydrogen atoms.

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The redistribution of iron implanted into the oxide layer of silicon-on-insulator structures has been measured using the secondary ion mass spectroscopy technique after annealing at 900–1050 °C. Iron diffusion has been found to be much faster in the oxide prepared by the separation-byimplantation-of-oxygen (SIMOX) procedure compared to the thermally grown oxide in the bonded and etched-back structures. In the latter case, the Fe diffusivity exhibits a thermal activation with an energy of 2.8 eV, confirming the literature data on silica glass. In the SIMOX oxide, the diffusivity depends only weakly on temperature, indicative of an essentially activation-free diffusion mechanism. Gettering of Fe at below-the-buried-oxide defects in SIMOX wafers has been observed. No iron segregation has been detected at the SiO2–Si interfaces.

Interstitial nickel in crystalline Si is shown to be a fast diffuser at room temperature. In this study, Ni is incorporated in Si by wet chemical etching in nickel-contaminated alkaline solutions. Nickel in-diffusion is observed by means of detecting the electrically active NiVO defect, which is formed due to Ni capture to the vacancy–oxygen complex in electron-irradiated Si. The depth profiles of the NiVO concentration measured by the deep-level transient spectroscopy technique extend to ∼15 μm in the samples doped with Ni at 35 °C for 30 min. This allows us to get a lower estimate for the nickel diffusivity at this temperature as 10−9 cm2/s. The activation energy for electron emission from the NiVO level and the apparent capture cross section are equal to 371 meV and 3 × 10−15 cm2, respectively. The NiVO complex dissociates at 300 °C reestablishing the initial concentration of the VO centers.