Structural characterization of a polycrystalline epitaxially-fused colloidal quantum dot superlattice by electron tomography

Abstract

We analyze the 3D structure of a 120×38 nm disc-shaped region of a PbSe QD epi-SL using full-tilt high-angle annular dark-field electron tomography. The high spatial resolution enables determination of the center-of-mass coordinates of all 1846 QDs in the sample as well as the size and shape of the thousands of epitaxial connections (necks) between the QDs. A map of the neck network is used to quantify relationships between neck number (the number of necks each QD possesses), average neck diameter, QD location in the film, and the nearest neighbor inter-QD distance and distance distribution. An electronic model demonstrates how neck distribution and SL defects reduce charge mobility.