Electron microscopy studies of electron‐beam sensitive PbTe‐based nanostructures

Falqui, Andrea; Bertoni, Giovanni; Genovese, Alessandro; Marras, Sergio; Malerba, Mario; Franchini, Isabella R.; Manna, Liberato

doi:10.1002/jemt.20843

Cited by 2 publications

(3 citation statements)

References 29 publications

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“…Lead chalcogenide-metal heterostructures. Falqui et al 197 have prepared PbTe NCs which were then treated with a solution of AuCl 3 in toluene and after depositing as a dry film, subsequently irradiated with an electron beam in vacuo. The treatment led to the formation of a mixture of several types of nanostructure: PbTe NCs coated with an amorphous layer of oxide, core-shells of crystalline gold coated with amorphous Pb x Te y Au z material, and gold particles attached to PbTe NCs.…”

Section: Pb Chalcogenidesmentioning

confidence: 99%

Narrow bandgap colloidal metal chalcogenide quantum dots: synthetic methods, heterostructures, assemblies, electronic and infrared optical properties

2013

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The chemistry, material processing and fundamental understanding of colloidal semiconductor nanocrystals (quantum dots) are advancing at an astounding rate, bringing the prospects of widespread commercialization of these novel and exciting materials ever closer. Interest in narrow bandgap nanocrystals in particular has intensified in recent years, and the results of research worldwide point to the realistic prospects of applications for these materials in solar cells, infrared optoelectronics (e.g. lasers, optical modulators, photodetectors and photoimaging devices), low cost/large format microelectronics, and in biological imaging and biosensor systems to name only some technologies. Improvements in fundamental understanding and material quality are built on a vast body of experience spread over many different methods of colloidal synthetic growth, each with their own strengths and weaknesses for different materials and sometimes with regard to particular applications. The nanocrystal growth expertise is matched by a rapidly expanding, and highly interdisciplinary, understanding of how best to assemble these materials into films or hybrid composites and thereby into useful devices, and again there are many different strategies that can be adopted. In this review we have attempted to survey and compare the recent work on colloidal synthesis, film and nanocrystal composite material fabrication, concentrating on narrow bandgap chalcogenide materials and some of their topical applications in the solar energy and biological fields. Since these applications are attracting rising interest across a wide range of disciplines, from the biological sciences, device engineering, and materials processing fields as well as the physics and synthetic chemistry communities, we have endeavoured to make the review of these narrow bandgap nanomaterials both comprehensive and accessible to newcomers to the area.

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Section: Pb Chalcogenidesmentioning

confidence: 99%

Narrow bandgap colloidal metal chalcogenide quantum dots: synthetic methods, heterostructures, assemblies, electronic and infrared optical properties

2013

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“…62 Unfortunately, due to the high sensitive of the electron beam, HRTEM of tiny PbTe nuclei cannot be obtained, which leads to uncertainty in the existence of the boundaries of nanocrystals. 63,64 In this chemical reaction system, the presence of TEA is expected to be key in governing the thermodynamic driving force for production of PbTe. The low supersaturation conditions of this reaction system were attributed to the low concentration of Pb 2+ released by the precursor Pb(TEA) 2 2+ , which was created to favor dislocationdriven crystal growth.…”

Section: Chemical Reaction Route and Possible Shape Evolution Formati...mentioning

confidence: 99%

New insights into the growth mechanism of hierarchical architectures of PbTe synthesized through a triethanolamine-assisted solvothermal method and their shape-dependent electrical transport properties

2013

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In this article, a triethanolamine (TEA)-assisted solvothermal method has been devised to synthesize PbTe hierarchical nanostructures on a large scale with various shapes, including octapodal dendrites with a spiral step hollow cubic center, hopper structures, and nanowires with branched nanorods, by tuning the amount of KOH and the volume ratio of the solvent. Systematic variation of the kinetic factors, including the reaction temperature, the duration time, the ratio of source materials, and the KOH concentration, reveals that the morphology depends mainly on the supersaturation degree of the free Pb 2+ ions released from Pb(TEA) 22+ under elevated temperature. The formation processes of the PbTe octapodal dendrites with a spiral step cubic center and nanowires with branched nanorods were believed to follow the screw dislocation-driven growth and in situ template and secondary nucleation route, according to the extensive experimental data. In addition, the electrical transport properties of the bulk samples consisting of octapodal dendrites, hopper structures, and nanowires with branched nanorods were measured to investigate the possible impact of the morphology on the electrical transport properties. The unusual electrical behaviors with temperature are attributed to charge carrier scattering at grain boundaries.

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“…We suggest that these features are ligand chains protruding from the nanocrystal edge, with several in superposition along the axis of the beam to generate sufficient contrast to be observed. It is possible to discount an alternative explanation, that the PbTe nanocrystals have formed an oxidized shell when exposed to atmosphere, 37 as the nanocrystals are passivated by ligands during synthesis.…”

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confidence: 99%

PbTe Nanocrystal Arrays on Graphene and the Structural Influence of Capping Ligands

Robertson

Ford

et al. 2014

Chem. Mater.

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The effective utilization of graphene in optoelectronic devices requires blending with other semiconductor materials, such as lead chalcogenide nanocrystals, and an understanding of the organic–inorganic interface at the atomic level. In this paper, we present the first report of the successful self-assembly of close-packed monolayer arrays of PbTe nanocrystals on monolayer graphene. By using ultraclean chemical vapor deposition grown graphene and aberration corrected transmission electron microscopy the unambiguous delineation of a ∼2 nm soft ligand nanocrystal shell is achieved, which is compared to subsequent studies after ligand exchange is performed on the same nanocrystal-graphene hybrid. Ligand exchange was shown to remove the soft ligand shell surrounding the nanocrystals and to disassemble the close-packed monolayers into amorphous nanocrystal aggregate film on the graphene substrate. Limited oriented attachment between nanocrystals in the anisotropic film was observed, and this was not significantly affected by extended vacuum annealing.

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Electron microscopy studies of electron‐beam sensitive PbTe‐based nanostructures

Cited by 2 publications

References 29 publications

Narrow bandgap colloidal metal chalcogenide quantum dots: synthetic methods, heterostructures, assemblies, electronic and infrared optical properties

Narrow bandgap colloidal metal chalcogenide quantum dots: synthetic methods, heterostructures, assemblies, electronic and infrared optical properties

New insights into the growth mechanism of hierarchical architectures of PbTe synthesized through a triethanolamine-assisted solvothermal method and their shape-dependent electrical transport properties

PbTe Nanocrystal Arrays on Graphene and the Structural Influence of Capping Ligands

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