engleski

NANO Si SUPERLATTICE FOR ADVANCED SOLAR CELLS

One approach for silicon based next generation solar cells relies on the production of suitable Si nanostructured objects in wide bandgap material. Present research on Si nanosize structures is focused on the Si nanocrystals prepared by sputtering of Si rich oxides and SiO2 multilayers on Si substrates. We present a study on amorphous SiO/SiO2 superlattice formation on Si substrate held at different elevated temperatures. Grazing-incidence small-angle X-ray scattering (GISAXS), X-ray reflectivity and photoluminescence were used to study such samples. From the 2D GISAXS pattern it is possible to determine the shape, size and inter-particle distance. Amorphous SiO/SiO2 superlattices were prepared by magnetron sputtering of 2nm thin films of SiO and SiO2 (10 layers each) from corresponding targets on silicon substrate. Rotation of the Si substrate during evaporation enables homogeneity of films over the whole substrate. After evaporation samples were annealed at 1050  C in different atmospheres. The analysis of the 2D GISAXS pattern has shown that Si nanocrystals are already present in the samples deposited at elevated temperatures. Using a Guinier approximation, the inter-nanocrystal distance and the thickness of the nanocrystals have been obtained. A long range ordering of nanocrystals deposited at elevated temperatures is observed.

nano silicon; superlattice; solar cells

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