Nanoscale fast Ge diffusion in laser irradiated SiGe thin films

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We report the presence of a fast Ge diffusion effect produced during laser crystallization of Si0.45Ge0.55 films deposited by magnetron sputtering on Si(100) substrates. The laser irradiation was performed using the 265 nm wavelength radiation of the Nd-YAG laser. After the irradiation with 10 laser pulses at a fluence of 30 mJ/cm2 the top part of the film shows two zones. Zone I, with a thickness of about 20 nm is crystallized and reach in Ge and the next zone in depth, i.e. Zone II, about 30 nm thickness, has a mixed crystalline and amorphous structure and is deficient in Ge, as revealed by the EDX line analysis. This can not be explained if we consider the usual value of 10-16 cm2/s for the Ge diffusion coefficient in SiGe and the short time of the laser heating. The redistribution of Ge by fast diffusion suggests a real diffusion coefficient of the order of magnitude of 10-4 cm2/s ,which can happen in liquids. However, the estimation of the top film temperature at the laser fluence of 30 mJ/cm2 is far from the melting point of SiGe film.

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Journal: TechConnect Briefs
Volume: 1, Nanotechnology 2013: Advanced Materials, CNTs, Particles, Films and Composites (Volume 1)
Published: May 12, 2013
Pages: 109 - 112
Industry sector: Advanced Materials & Manufacturing
Topic: Materials Characterization & Imaging
ISBN: 978-1-4822-0581-7