engleski

Formation of Ge nanocrystals in SiO2 substrate by magnetron sputtering and post-deposition thermal treatment

We performed grazing incidence small angle x-ray scattering (GISAXS), Raman and Rutherford-Back-Scattering study of the formation Ge nanoparticles in SiO2 matrix, produced by magnetron sputtering deposition. Ge and SiO2 are deposited simultaneously with Ge (atoms): SiO2 (molecules) ratio 40:60 on SiO2 substrate. Influence of deposition conditions and thermal annealing after deposition process on formed nanoparticles properties are analyzed. Five different deposition conditions on SiO2 substrate are analyzed: (i) one layer with thickness 340 nm deposited at room temperature, (ii) 15 bilayers, with composition Ge+SiO2/SiO2, with thickness 8 nm of each layer, deposited at room temperature, (iii) the same procedure as (ii) but with deposition temperature 500 - 7000C, (iv) 15 bilayers, with composition Ge-SiO2 layer 4 nm thick and SiO2 layer 8 nm thick, deposited at room temperature (v) the same structure as (iv) but with deposition temperature 500-7000C. As-deposited samples are subsequently thermally annealed up to10000C. We found strong dependence of nanoparticles sizes and depth distribution on the deposition and annealing conditions. We also found the best regime of parameters for formation spherical, completely crystalline Ge nanoparticles. The average size of the nanocrystals at a given annealing temperature can be controlled by the thickness of the Ge-SiO2 co-sputtered layer. Special effects are obtained for 8+8 nm bilayers and 500o C deposition, when 3D lattice of Ge nanocrystals can be formed.

Ge nanocrystals; annealing; magnetron sputtering deposition

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