HeteroBN-C (2020-2024)

One-dimensional Van der Waals Heterostructures

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The proposal HETEROBN-C aims at the controlled synthesis of freestanding one dimensional (1D) hexagonal Boron Nitride (hBN)/Carbon nanotube (CNTs) van der Waals (VdW) heterostructures and at the investigation of their structural and optical properties. In line with the spectacular improvement and emergence of new physical properties in 2D VdW heterostructures, the curvature and confinement effects provided by the reduced dimensionality of 1D VdW heterostructures make them highly attractive. These new 1D materials are of particular interest for applications ranging from sensing and quantum optics, to biological labeling. The project will focus on the understanding of the controlled growth of hBN by atomic layer deposition (ALD) onto/into suspended single wall CNTs as well as on the investigation of the relationship between the structure and the optical properties (excitonic luminescence yield, spectral properties, …). Particular attention will be paid at developing highly-controlled method of hBN deposition inside and outside CNTs, studying the growth mechanism and the resulting interaction at the nanoscale. In this regard, single-wall carbon nanotubes (SWCNTs), used as support, will be coated with a thin (from a few nm down to one monolayer) hBN layer using ALD. By means of advanced analytic transmission electron microscopy combined with DFT calculation, the relationship between the deposited hBN and the graphitized carbon support will be deeply investigated as the function of the fabrication parameters. Understanding of the BN growth on the inner and outer part of the SWCNT wall is indeed the key for a fine tuning of VdW heterostructure interfaces. On the optical side, the interface features (inter-tube spacing, orientational correlation…), expected to strongly influence the VdW coupling and thus the electronic and optical properties of this 1D heterostructure, will be studied both (1) in the near-IR spectral domain of the CNT optical response in the prospect of reaching the intrinsic limit (truly one-dimensional radiative-limited excitonic emission) of the CNT properties thanks to the hBN-encapsulation, and (2) in the deep-UV spectral domain of the BN optical response for observing the luminescence of BN layer deposited in the inner CNT wall.

HeteroBN-C brings together the Laboratoire des Multimatériaux et Interfaces (LMI) at Lyon, the Laboratoire Charles Coulomb (L2C) at Montpellier, the Laboratoire de Physique de l’ENS (LPENS) at Paris, and the Laboratoire de Modélisation et Exploration des Matériaux (MEM) at Commissariat à l’énergie atomique et aux énergies alternatives (CEA) of Grenoble for a period of 4 years.

Project overview

Connecting two different materials as easily as Lego® bricks at the atomic scale to combine their intrinsic properties or to create new ones has long seemed an elusive dream until the recent realization that the perfect glue already exists, neither too weak, nor too strong: Van der Waals (VdW) coupling. This concept has been successfully implemented with a large variety of 2D materials (graphene, hexagonal boron nitride (hBN), dichalcogenides…) driving a blooming research activity. While the electronic and optical properties of materials deposited on regular substrates (Si/SiO2) are dramatically altered by the random interaction with the substrate (including charge noise in transport, spectral diffusion and blinking in optics…), combining hBN and graphene in 2D VdW heterostructures has constituted a key breakthrough for the performance of electronic nanodevices as it suppresses the scattering of charge carriers by environmental defects. Conversely, graphitized carbon (C) was demonstrated to be a suitable optical substrate for hBN in addition to a near perfect lattice-matched growth template.

By analogy with 2D materials, 1D heterostructures made of carbon nanotube (CNT) coated by hBN shell with close lattice-matching should have greatly improved properties close to the intrinsic limits of CNTs. Reciprocally these 1D heterostructures would open new perspectives with regards to the opto-electronic properties of pristine BN nanotubes.

The proposal HeteroBN-C aims at the controlled synthesis of freestanding 1D hBN/CNT heterostructures and at the investigation of their structural and optical properties.

On the chemistry side, the controlled design of such new 1D heterostructures raises new challenges and questions due to the high surface curvature and quantum confinement of nanotubes. Attention will be paid at developing highly-controlled method of hBN deposition inside and outside CNTs, studying the growth mechanism and the resulting interaction at the nanoscale. In this regard, single-wall carbon nanotubes (SWCNTs), used as support, will be coated with a thin (from a few nm down to one monolayer) hBN film. To design 1D VdW heterostructures, control of the thickness and crystallinity (phase, grain size, lattice matching with SWCNTs) of the deposited BN is required. Atomic layer deposition (ALD) appears as the technique of choice as it allows fine control of the film thickness at the atomic level. Using this approach, VdW stacking is expected in this case. Understanding of the BN growth on the inner and outer part of the SWCNT wall is the key for a fine tuning of VdW heterostructure interfaces. On the optical side, the interface features (inter-tube spacing, orientational correlation…) are expected to strongly influence the VdW coupling and thus the electronic and optical properties of this 1D heterostructure. The project objectives are:

  • Obj. 1. Study of the epitaxial relationship between ALD hBN and unfunctionalized CNTs.
  • Obj. 2. Controlled synthesis and design of 1D hBN/CNT heterostructures.
  • Obj. 3. Study of hBN/CNT heterostructures (a) in the near-IR spectral domain of the CNT optical response in the prospect of reaching the intrinsic limit (truly one-dimensional radiative-limited excitonic emission) of the CNT properties thanks to the hBN-encapsulation, and (b) in the deep-UV spectral domain of the BN optical response for observing the luminescence of single-wall BN nanotube encapsulated by the CNT.

To achieve these objectives, the project is divided into 3 work-packages.

Concept of the project.

Researchers

The project will benefit from the complementary expertise of the four academic partners of the consortium. The laboratoire des Multimatériaux et Interfaces (LMI) coordinates HeteroBN-C and synthesizes and characterizes the BN layers using ALD as well as study the BN growth mechanism. The laboratoire Charles Coulomb (L2C) is in charge of the fabrication of individual suspended SWCNTs and their structural characterization by absorption spectroscopy (using a new optical setup specially developed for studying individual 1D nanostructures) and resonant Raman spectroscopy (at different laser energies in the visible range). The opto-electronic properties of hBN are also investigated by L2C. The laboratoire de Physique de l’ENS (LPENS) characterizes the hBN/CNT heterostructures in the near-IR spectral domain of the CNT optical response. The laboratoire de Modélisation et Exploration des Matériaux (MEM) works on structural and chemical characterization of hBN-C heterostructures using Low-Voltage Aberration corrected TEM (LVAC-TEM) and energy loss spectroscopy (EELS). It also produces DFT calculations to understand the atomic structure of C-BN tubes, especially the epitaxial correlation between C- and BN-nanotubes.

Researchers from LMI @ UCBL


Dr. Catherine Marichy (PI, coordinator) is a CNRS researcher at UCBL since 2013. She is an expert on ALD. Her research focuses on the development of new ALD approaches for functional materials, the understanding of the underlying mechanisms and the investigation of the structure-properties relationship. She especially works on the deposition of metal oxides and h-BN as well as on the fabrication of h-BN/C heterostructures.


Pr. Catherine Journet is Full Professor at UCBL and is leading the research group on low-dimensionality materials whose main activities are related to the synthesis of micro- and nanostructures, the study of the interfaces structuration during synthesis, and the physico-chemical properties of the fabricated materials. She is among the pioneering scientists in the nanotube field and an expert in the synthesis techniques of C and BN 1D and 2D nanostructures. Her research mainly focuses on the synthesis and characterization of 2D and 1D BN- and C-based nanomaterials. Currently, she is involved in the synthesis of BN-based 2D materials and heterostructures. She is author of about ~80 scientific peer-reviewed papers for a total of more than 8000 citations.

Researchers from L2C @ Univ. Montpellier


Vincent Jourdain is Professor at the Université de Montpellier. His main interests are the physics and chemistry of carbon nanotubes, especially including their growth mechanisms, their nanofluidic properties and their optical characterization. His approach notably involved in situ measurements by Raman spectroscopy, polarized optical imaging, and low-noise electrical measurements. He is expert in the elaboration and structural characterization of individual SWCNTs.



Prof. Guillaume Cassabois is an expert in the optical spectroscopy of nanostructures, with recent interest in the opto-electronic properties of hBN and contributions defining the state-of-the-art in the field.



Said Tahir is Assistant Engineer at CNRS. At L2C, he is in charge of the fabrication and characterization of suspended single-walled CNTs using techniques such as microfabrication techniques in clean room, CVD, SEM and TEM.

Researchers from LPENS @ Paris


Prof. Christophe Voisin is Full professor at Université de Paris and director of the GDR 3017 “Graphene and co” coordinating national research efforts on graphene and related materials (including their heterostructures and 1D counterparts). He is an expert in the optical properties of nanostructures at the single nano-object level including CNTs and graphene/hBN 2D devices. He was coordinator and partner of several former ANR projects.

Dr. Yannick Chassagneux

Researchers from CEA @ Grenoble


Dr. Hanako Okuno is an expert in high resolution TEM and associated techniques. She obtained her Master Degree in Materials Science and Engineering from Tokyo Institute of Technology in 1999. She received PhD in Materials Science from Louvain catholic University in Belgium, entitled “Synthesis and characterization of carbon based materials” in 2006. She worked in advanced microscopy to develop quantitative chemical atomic resolution imaging on semiconductor during her post-doc fellows before joining CEA LITEN in 2009 where she worked on the integration of CNTs in microelectronic applications. She joined CEA INAC in 2011 and is in charge of advanced microscopy for carbon-based materials at Nano-characterization platform.


Dr. Pascal Pochet is a research director at CEA specialized in computational materials science. He received an engineering degree in chemistry from the ENSCL school in Lille in 1992. He worked as a PhD student on the ball-milling induced phase transformation both from experimental and theoretical point of view from 1993 to 1997. In 1999 he joined the CEA organization as a permanent research staff member working on several theoretical topics related with defense applications. In 2005, he joined the CEA basic research division. He is a specialist of atomistic simulation in the field of point defect engineering and nanostructure growth. He applies Kinetic Lattice Monte Carlo and DFT methods to calculate point defect properties in semiconductors and 2D materials in the field of microelectronics and energy applications.


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