Fast Diffusion of Metastable Vacancies in Surface of Excited Si Crystals

A.J. Janavičiusa and S. Turskienėb aFaculty of Natural Sciences,Šiauliai University, Višinskio 25, Šiauliai, 76351, Lithuania bFaculty of Mathematics and Informatics,Šiauliai University, Višinskio 19,Šiauliai, 76351, Lithuania

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Received: 19 6 2006;

We considered the practically interesting, very fast nonlinear diffusion of metastable vacancies in the surface of Si crystal, excited by soft X-rays. Here we used experimentally defined diffusion coefficients of singly and doubly negatively charged very fast vacancies generated by soft X-rays. These high concentration (about 1013 cm-3) metastable vacancies at room temperature can diffuse and exist in the crystal for a very long time (about 24 hours for not so fast neutral vacancies) changing electrical conductivity, the Hall mobility of carriers and generating some resonance phenomena in the lattice of Si crystal. We measured superdiffusivity of negatively charged vacancies, generated by the Auger effect in the regions of the sample, where X-rays did not acted. In the paper we modified the formerly obtained analytical solution of nonlinear diffusion equation for calculation of distribution of vacancies in two-dimensional surface.

DOI: 10.12693/APhysPolA.110.505 PACS numbers: 66.30.-h, 66.30.Hs, 78.70.Ck