Size dependence in tunneling spectra of PbSe quantum-dot arrays

Increased conductance of individual self-assembled GeSi quantum dots by inter-dot coupling studied by conductive atomic force microscopy

The conductive properties of individual self-assembled GeSi quantum dots (QDs) are investigated by conductive atomic force microscopy on single-layer (SL) and bi-layer (BL) GeSi QDs with different dot densities at room temperature. By comparing their average currents, it is found that the BL and high-density QDs are more conductive than the SL and low-density QDs with similar sizes, respectively, indicating the existence of both vertical and lateral couplings between GeSi QDs at room temperature. On the other hand, the average current of the BL QDs increases much faster with the bias voltage than that of the SL QDs does. Our results suggest that the QDs' conductive properties can be greatly regulated by the coupling effects and bias voltages, which are valuable for potential applications.

Unexpected electronic properties of micrometer-thick supracrystals of Au nanocrystals

We investigated the electronic properties of highly ordered three-dimensional colloidal crystals of gold nanocrystals (7 ± 0.4 nm), called supracrystals. Two kinds of Au supracrystals with typical thicknesses of 300 nm and 5 μm, respectively, are probed for the first time with scanning tunneling microscopy/spectroscopy at 5 K revealing similar power law behavior and showing homogeneous conductance with the fingerprint of isolated nanocrystal. Potential applications evading the size-related risks of nanocrystals could be then considered.