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Strong Modulations of Optical Reflectance in Tapered Core-Shell Nanowires. MATERIALS 2019; 12:ma12213572. [PMID: 31683526 PMCID: PMC6862277 DOI: 10.3390/ma12213572] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 10/21/2019] [Accepted: 10/28/2019] [Indexed: 12/21/2022]
Abstract
Random assemblies of vertically aligned core–shell GaAs–AlGaAs nanowires displayed an optical response dominated by strong oscillations of the reflected light as a function of the incident angle. In particular, angle-resolved specular reflectance measurements showed the occurrence of periodic modulations in the polarization-resolved spectra of reflected light for a surprisingly wide range of incident angles. Numerical simulations allowed for identifying the geometrical features of the core–shell nanowires leading to the observed oscillatory effects in terms of core and shell thickness as well as the tapering of the nanostructure. The present results indicate that randomly displaced ensembles of nanoscale heterostructures made of III–V semiconductors can operate as optical metamirrors, with potential for sensing applications.
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Gemmi M, Mugnaioli E, Gorelik TE, Kolb U, Palatinus L, Boullay P, Hovmöller S, Abrahams JP. 3D Electron Diffraction: The Nanocrystallography Revolution. ACS CENTRAL SCIENCE 2019; 5:1315-1329. [PMID: 31482114 PMCID: PMC6716134 DOI: 10.1021/acscentsci.9b00394] [Citation(s) in RCA: 203] [Impact Index Per Article: 40.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Indexed: 05/20/2023]
Abstract
Crystallography of nanocrystalline materials has witnessed a true revolution in the past 10 years, thanks to the introduction of protocols for 3D acquisition and analysis of electron diffraction data. This method provides single-crystal data of structure solution and refinement quality, allowing the atomic structure determination of those materials that remained hitherto unknown because of their limited crystallinity. Several experimental protocols exist, which share the common idea of sampling a sequence of diffraction patterns while the crystal is tilted around a noncrystallographic axis, namely, the goniometer axis of the transmission electron microscope sample stage. This Outlook reviews most important 3D electron diffraction applications for different kinds of samples and problematics, related with both materials and life sciences. Structure refinement including dynamical scattering is also briefly discussed.
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Affiliation(s)
- Mauro Gemmi
- Center
for Nanotechnology Innovation@NEST, Istituto
Italiano di Tecnologia, Piazza S. Silvestro 12, 56127 Pisa, Italy
| | - Enrico Mugnaioli
- Center
for Nanotechnology Innovation@NEST, Istituto
Italiano di Tecnologia, Piazza S. Silvestro 12, 56127 Pisa, Italy
| | - Tatiana E. Gorelik
- University
of Ulm, Central Facility for Electron Microscopy, Electron Microscopy
Group of Materials Science (EMMS), Albert Einstein Allee 11, 89081 Ulm, Germany
| | - Ute Kolb
- Institut
für Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universität, Duesbergweg 10-14, 55128 Mainz, Germany
- Institut
für Angewandte Geowissenschaften, Technische Universität Darmstadt, Schnittspahnstraße 9, 64287 Darmstadt, Germany
| | - Lukas Palatinus
- Department
of Structure Analysis, Institute of Physics
of the CAS, Na Slovance 2, 182 21 Prague 8, Czechia
| | - Philippe Boullay
- CRISMAT,
Normandie Université, ENSICAEN, UNICAEN, CNRS UMR 6508, 6 Bd Maréchal Juin, F-14050 Cedex Caen, France
| | - Sven Hovmöller
- Inorganic
and Structural Chemistry, Department of Materials and Environmental
Chemistry, Stockholm University, 106 91 Stockholm, Sweden
| | - Jan Pieter Abrahams
- Center
for Cellular Imaging and NanoAnalytics (C−CINA), Biozentrum, Basel University, Mattenstrasse 26, CH-4058 Basel, Switzerland
- Department
of Biology and Chemistry, Paul Scherrer
Institut (PSI), CH-5232 Villigen PSI, Switzerland
- Leiden
Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
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Zamani RR, Arbiol J. Understanding semiconductor nanostructures via advanced electron microscopy and spectroscopy. NANOTECHNOLOGY 2019; 30:262001. [PMID: 30812017 DOI: 10.1088/1361-6528/ab0b0a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Transmission electron microscopy (TEM) offers an ample range of complementary techniques which are able to provide essential information about the physical, chemical and structural properties of materials at the atomic scale, and hence makes a vast impact on our understanding of materials science, especially in the field of semiconductor one-dimensional (1D) nanostructures. Recent advancements in TEM instrumentation, in particular aberration correction and monochromation, have enabled pioneering experiments in complex nanostructure material systems. This review aims to address these understandings through the applications of the methodology for semiconductor nanostructures. It points out various electron microscopy techniques, in particular scanning TEM (STEM) imaging and spectroscopy techniques, with their already-employed or potential applications on 1D nanostructured semiconductors. We keep the main focus of the paper on the electronic and optoelectronic properties of such semiconductors, and avoid expanding it further. In the first part of the review, we give a brief introduction to each of the STEM-based techniques, without detailed elaboration, and mention the recent technological and conceptual developments which lead to novel characterization methodologies. For further reading, we refer the audience to a handful of papers in the literature. In the second part, we highlight the recent examples of application of the STEM methodology on the 1D nanostructure semiconductor materials, especially III-V, II-V, and group IV bare and heterostructure systems. The aim is to address the research questions on various physical properties and introduce solutions by choosing the appropriate technique that can answer the questions. Potential applications will also be discussed, the ones that have already been used for bulk and 2D materials, and have shown great potential and promise for 1D nanostructure semiconductors.
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Affiliation(s)
- Reza R Zamani
- Department of Physics, Chalmers University of Technology, Gothenburg, SE-41296, Sweden. Interdisciplinary Centre for Electron Microscopy (CIME), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne 1015, Switzerland
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