Determination of diffusivities of Si self-diffusion and Si self-interstitials using isotopically enriched single-or multi-30Si epitaxial layers

S. Matsumoto, S. R. Aid, T. Sakaguchi, K. Toyonaga, Y. Nakabayashi, M. Sakuraba, Y. Shimamune, Y. Hashiba, J. Murota, K. Wada, T. Abe

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Self-diffusivity of Si has been obtained over a wide temperature range (867°C-1300°C) using highly isotopically enriched 30Si epi-layers (99.88%) as a diffusion source into natural Si substrates. 30Si epi-layers were grown on both CZ-Si substrates and non-doped epi-layers grown on CZ-Si substrates using low pressure CVD with 30SiH4. Diffusion was performed in resistance-heated furnaces under a pure Ar atmosphere. After annealing, the concentrations of the respective Si isotopes were measured with secondary ion mass spectroscopy (SIMS). Diffusivity of 30Si (called Si self-diffusivity, D SD) was determined using a numerical fitting process with 30Si SIMS profiles. We found no major differences in self-diffusivity between bulk Si and epi-Si. Within the 867°C-1300°C range investigated, DSD can be described by an Arrhenius equation with one single activation enthalpy: DSD =14 exp (-4.37 eV/kT) cm2/s. The present result is in good agreement with that of Bracht et. al. Diffusivity and thermal equilibrium concentration of Si self-interstitials have been determined using multi-30Si epi-layers consisting of alternative layers with isotopically pure 30Si and natural Si. The sample surface was oxidized and the Si self-interstitials were introduced from the surface. Spreading of 30Si spikes of each layer due to the diffusion of Si self-interstitials generated at the surface was measured with SIMS analysis. The diffusivity of Si self-interstitials, D I, is obtained by fitting with experimental results. In the temperature range between 820 920°C, DI and thermal equilibrium concentration of Si self-interstitials, CIi, are described by the Arrhenius equations DI =3.48 × 104 exp(-3.82eV/W) cm2/s and CIi = 9.62 × 1018 exp(- 0.475eV/kT) cm-3, respectively.

Original languageEnglish
Article numberE8.4
Pages (from-to)425-436
Number of pages12
JournalMaterials Research Society Symposium Proceedings
Publication statusPublished - 2005
Event2005 materials Research Society Spring Meeting - San Francisco, CA, United States
Duration: 2005 Mar 282005 Apr 1


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