High-Mobility Hole Transport in Single-Grain PbSe Quantum Dot Superlattice Transistors.
basic_science · Level V
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- Record sourced from PubMed, PMID 36411037.
- Also identified by DOI 10.1021/acs.nanolett.2c03657 and PMC identifier 9756332.
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Abstract
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 <i>p</i>-channel or ambipolar transport with a hole mobility as high as 3.5 cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup> at 290 K and 6.5 cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup> 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.