High-Mobility Hole Transport in Single-Grain PbSe Quantum Dot Superlattice Transistors.

Nano Lett

Department of Materials Science and Engineering, University of California, Irvine, Irvine, California 92697, United States.

Published: December 2022

Epitaxially-fused superlattices of colloidal quantum dots (QD epi-SLs) may exhibit electronic minibands and high-mobility charge transport, but electrical measurements of epi-SLs have been limited to large-area, polycrystalline samples in which superlattice grain boundaries and intragrain defects suppress/obscure miniband effects. Systematic measurements of charge transport in individual, highly-ordered epi-SL grains would facilitate the study of minibands in QD films. Here, we demonstrate the air-free fabrication of microscale field-effect transistors (μ-FETs) with channels consisting of single PbSe QD epi-SL grains (2-7 μm channel dimensions) and analyze charge transport in these single-grain devices. The eight devices studied show -channel or ambipolar transport with a hole mobility as high as 3.5 cm V s at 290 K and 6.5 cm V s at 170-220 K, one order of magnitude larger than that of previous QD solids. The mobility peaks at 150-220 K, but device hysteresis at higher temperatures makes the true mobility-temperature curve uncertain and evidence for miniband transport inconclusive.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9756332PMC
http://dx.doi.org/10.1021/acs.nanolett.2c03657DOI Listing

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