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The past decade has seen the explosion of experimental results on nanowires grown by catalyzed mechanisms. However, few are known on their electronic properties especially the influence of surfaces and catalysts. We demonstrate by an optical method how a curious electron-hole thermodynamic phase can help to characterize volume and surface recombination rates of silicon nanowires (SiNWs). By studying the electron-hole liquid dynamics as a function of the spatial confinement, we directly measured these two key parameters. We measured a surface recombination velocity of passivated SiNWs of 20 cm s(-1), 100 times lower than previous values reported. Furthermore, the volume recombination rate of gold-catalyzed SiNWs is found to be similar to that of a high-quality three-dimensional silicon crystal; the influence of the catalyst is negligible. These results advance the knowledge of SiNW surface passivation and provide essential guidance to the development of efficient nanowire-based devices.

We present a detailed study of the electronic properties of individual silicon nanocrystals (nc-Si) elaborated by low-pressure chemical vapor deposition on 1.2 nm thick SiO2 grown on Si (100). The combination of ultrathin oxide layers and highly doped substrates allows the imaging of the hemispherical dots by scanning tunneling microscopy. Spectroscopic studies of single dots are made by recording the I(V) curves on the Si nanocrystal accurately selected by a metallic tip. These I(V) curves exhibit Coulomb blockade and resonant tunneling effects. Coulomb pseudogaps between 0.15 and 0.2 V are measured for different dots. Capacitances between 0.2 and 1 aF and tunnel resistances around 5×109 Ω are deduced from the width and height of the staircases. The charging and confinement energies deduced from the I(V) curves are in good agreement with a modified orthodox model which includes the quantification of electronic levels.