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Research Highlight

Distinct electronic states revealed in coherent quantum dot superlattices

(a) STEM image of PbSe quantum dots. (b) Local tunneling image from two-probe STM/S measurement. (c) STS spectra from body (R1) and neck (R2) showing change in bandgap. Monochromated EELS maps of (d) bulk electronic structure and (e) emergent electronic structure.

Scientific Achievement

Local electronic states in epitaxially fused PbSe quantum dot superlattices have been characterized for the first time.

Significance and Impact

The spectrally sharp quantum confined states arise from the "necks" connecting adjacent dots, which modifies the energy landscape and can result in renormalization of conduction channels in optoelectronic devices and even topological electronics built on superlattice solids.

Research Details

  • Multi-probe STM was used to probe local electronic states.
  • Modulation of the electronic structure along with the corresponding atomic structure was confirmed with monochromated STEM-EELS.
  • By using the machine learning technique, non-negative matrix factorization, nanoscale maps of the emergent structure were obtained.

M.S. Kavrik, et al., Nature Communications 13, 6802 (2022).  DOI: 10.1038/s41467-022-33955-w

Work performed at the Center for Nanophase Materials Sciences, Lawrence Berkeley National Laboratory, University of California San Diego, and University of California Irvine.