研究目的
Investigating the orientational disorder in epitaxially connected quantum dot solids and its implications for electronic bandstructure control.
研究成果
The study reveals significant orientational disorder in epitaxially connected quantum dot solids, with misalignments persisting despite coherent atomic connectivity. The findings suggest that simplified models of epitaxial attachment may be insufficient to understand quantum dot growth and disorder, highlighting the need for further refinement of growth techniques to minimize disorder and achieve desired electronic properties.
研究不足
The study is limited by the complexity of film growth and the presence of structural disorder, which may affect the electronic properties of quantum dot solids. The irreversibility of the oriented attachment process and the geometric frustration in the superlattice structure are also limitations that could influence the final film quality.
1:Experimental Design and Method Selection:
Aberration-corrected scanning transmission electron microscopy (STEM) with a high-angle annular dark-field (HAADF) detector was used to obtain high-resolution Z-contrast images.
2:Sample Selection and Data Sources:
Films of epitaxially connected PbSe QDs were fabricated and prepared for STEM imaging.
3:List of Experimental Equipment and Materials:
NION UltraSTEM at an accelerating voltage of 60kV, convergence angle of 30 mrad, and signal collected from a HAADF detector with an inner collection angle of 80 mrad.
4:Experimental Procedures and Operational Workflow:
Samples were transferred to lacey carbon grids coated with ultrathin carbon using the Langmuir-Schaefer method, rinsed in anhydrous methanol and acetonitrile, and dried under vacuum before imaging.
5:Data Analysis Methods:
Orientation information of individual QDs was extracted from their atomic lattices using an in-house algorithm, and bond orientational order metric ψ4 was used to quantify local superlattice orientation.
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