ИСТИНА

Semiconductor nanocrystals are investigated for their functional properties combined with potential colloidal solubility they possess. One of such properties is localized surface plasmon resonance (LSPR) found in heavily doped nanocrystals - a feature potentially useful for fabrication of logic gates in photonics, as well as for redox sensing. Spectral position of LSPR band in dependent on the quantity of charge carriers, so it is possible to tune it dynamically. However, the nature of the dependence is yet unclear in case of nanosilicon, as there is contradictory evidence on the preferential position of impurities and on the role of surface passivation. Here we report on a novel approach to studying the radial distribution of impurities in Si nanocrystals, comprised of multiple steps of subsequent HF gas phase etch in PTFE chamber and oxidation of sample in O2 gas flow. It is possible to obtain IR spectra during oxidation and thus study radial distribution of the impurity in plasmonic samples in great detail. The particles studied were synthesized with diffusion doping technique [1]. We have established the synthetic conditions necessary to obtain phosphorus- and boron-doped Si nanocrystals with highly uniform distribution of electrically active impurity (Fig.1). The position of their LSPR band is largely insensitive to the chemical composition of surface (Si-H or silicon oxide), which allows to attribute the feature exactly to the concentration of electrically active impurity in the Si cores.