Experimental and theoretical investigation of electronic and atomic structure of Si-nanocrystals formed in sapphire by ion implantation

Kovalev, Anatoly1; Wainstein, Dmitry1; Tetelbaum, David1; Mikhailov, Alexey1; Bulutay, Ceyhun2; Aydinli, Atilla2; Finstad, Terje3; Foss, Steinar3 1Russian Federation; 2Turkey; 3Norway

The semiconductor nanocomposites based on Si nanocrystals in dielectric matrices attract a great amount of attention due to its ability for luminescence in visible and near-IR part of the spectrum. Si nanocrystals in sapphire matrix were formed by Si+ ions implantation with doses from 5x10¹⁶ to 3x10¹⁷ cm^-2 at an accelerating voltage 100 kV and post-implantation annealing at 500 - 1100 ^oC. The features of chemical, electronic and atomic structure were determined using depth profiling. Depth distribution of the elements and were determined using XPS. The depth distribution of lattice defects, impurities and Si nanocrystals, the peculiarities of interband electronic transitions were investigated by HREELS. The accommodation strain at the "Si-nc / sapphire matrix" interface was determined by EELFS. The MO’s and local electronic structure of the Al₂O₃ matrix with Si nanocrystals was calculated using the atomistic pseupotential technique. The electronic structure of Si nanocrystals as determined from HREELS measurements is in good agreement with the theoretically calculated electronic structure for Si nanocrystals with diameters of 2 – 3 nm as determined by HR TEM.
Acknowledgements. The work was partly supported by the European Commission through the FP6 project SEMINANO Contract No: NMP4-CT-2004-505285, and by RF State Contract 3662p/4844 provided by FASIE.

---

back