Room-Temperature Electron Transport in Self-Assembled Sheets of PbSe Nanocrystals with a Honeycomb Nanogeometry
Résumé
ABSTRACT:
It has been shown recently that atomically
coherent superstructures of a nanocrystal monolayer in
thickness can be prepared by self-assembly of monodisperse
PbSe nanocrystals, followed by oriented attachment.
Superstructures with a honeycomb nanogeometry are of special interest, as theory has shown that they are regular 2-D semiconductors, but with the highest valence and lowest conduction bands being Dirac-type, that is, with a linear energy-momentum relation around the K-points in the zone.
Experimental validation will require cryogenic measurements on single sheets of these nanocrystal monolayer superstructures.
Here, we show that we can incorporate these fragile superstructures into a transistor device with electrolyte gating, control the electron density, and measure the electron transport characteristics at room temperature. The electron mobility is 1.5 ± 0.5 cm2 V−1 s−1, similar to the mobility observed with
terahertz spectroscopy on freestanding superstructures. The terahertz spectroscopic data point to pronounced carrier scattering
on crystallographic imperfections in the superstructure, explaining the limited mobility
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