Evidence for room-temperature in-diffusion of nickel into silicon

Abstract

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.

Nickel Interaction with Vacancy‐Type Radiation Defects in Silicon

“…Comparison with Cz‐Si : The DLTS peak of Ni V O, the complex formed as a result of Ni and A‐center interaction, was shown to appear at ≈180 K too . In the FZ samples this peak is hidden in the much stronger Ni V P signal.…”

“…However, the parameters of the dominant centers in each sample were obtained with acceptable accuracy from the unresolved LDLTS spectra. For example, the activation energy and capture cross section measured in this work for the Ni V O complex are nearly identical to those obtained in the lower‐doped samples where the V P center concentration was negligible …”

“…Comparison with Cz-Si: The DLTS peak of NiVO, the complex formed as a result of Ni and A-center interaction, was shown to appear at %180 K too. [4] In the FZ samples this peak is hidden in the much stronger NiVP signal. The similar positions of the DLTS peaks from NiVP and NiVO centers is surprising since their precursors, the A-and E-centers, have quite different structures and level positions.…”

“…Nickel is known to be detrimental to silicon‐based electronic devices because of the extremely high diffusivity and many possible sources of nickel contamination . Recently, we showed that nickel can penetrate into silicon even at room temperatures and form complexes with radiation defects . In particular, nickel interaction with the vacancy–oxygen pair ( V O, A‐center) resulted in formation of the Ni V O complex with an acceptor level at 0.37 eV below the bottom of the conduction band.…”

“…[1][2][3] Recently, we showed that nickel can penetrate into silicon even at room temperatures and form complexes with radiation defects. [4,5] In particular, nickel interaction with the vacancy-oxygen pair (VO, A-center) resulted in formation of the NiVO complex with an acceptor level at 0.37 eV below the bottom of the conduction band. In the present work, the study of nickel impact on the radiation damage is extended to another vacancy-type defect, the vacancy-phosphorus (VP) pair.…”