Inhibited single-electron transfer by electronic band gap of two-dimensional Au quantum dot superlattice
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Schematic representation of three types of DBTJ studied: a NP is linked to two leads via two tunnel junctions. and are the Fermi level of lead 1 and lead 2, respectively. and are the tunneling rate into and out the NP, respectively. (a) Schematic representation of metal-metal-metal DBTJ (upper panel) and the corresponding differential conductance (lower panel), which reveals uniform oscillation periodicity with voltage widths of . (b) Schematic representation of metal-semiconductor-metal DBTJ (upper panel) and the corresponding differential conductance (lower panel). is the band gap of the semiconductor NP. (c) Schematic representation of metal-metal-semiconductor DBTJ (upper panel) and the corresponding differential conductance (lower panel). is the band gap of the semiconductor lead.
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(a) A typical TEM image of the 2D Au NPs. The TEM image with selected area electron diffraction showed that the Au NPs had a distribution of sizes centered at diameter of about 4.3 nm. (b) A typical STM image of 2D Au quantum dot superlattice on HOPG. The image is taken in a constant-current scanning mode with a tunneling current of 113 pA and a bias voltage of –1.88 V. (c) A typical curve obtained on the 2D Au superlattice. It reveals similar band gap structure as semiconductor. (d) A typical curve obtained when one Au NP is adhered to STM tip. The uniform oscillation periodicity with voltage widths of at high voltage bias is ascribed to the Coulomb blockade. The differential conductance oscillation of the Au NP is effectively inhibited from about –0.2 eV to about 1.5 eV.
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