(Invited) ALD of Hexagonal Boron Nitride: Towards h-BN/Carbon Van Der Waals 1D Heterostructures

Abstract

Following the graphene isolation, strong interest in two dimensional (2D) materials has been driven by their outstanding properties. Their typical intrinsic structure, including strong in-plane covalent bonding and weak out-of-plane Van der Waals interaction, makes them highly promising in diverse areas such as electronics, catalysis, and environment. Growth of 2D materials and staking of such materials, called van der Waals (VdW) heterostructures, require a synthesis approach able to control the deposition onto a support at the atomic scale. Thanks to their simplicity, versatility and ability to control thickness at the angstrom level, Atomic Layer Deposition (ALD) and its variant Atomic Layer Etching (ALET) appear as ones of the most suited techniques to synthesize 2D materials and based-heterostructures. 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.Herein, ALD of hexagonal Boron Nitride (hBN) is discussed towards fabrication of VdW heterostructures. After introducing the two-step ALD approach for BN, based on polymer derived ceramic chemistry, deposition of hBN onto various carbon nanomaterials is presented. The influence of the degree of graphitization of the carbon substrate on BN growth (nucleation delay) and structure (amorphous, turbostratic, hexagonal phase) is discussed. Indeed, inertness of highly graphitic carbon might inhibit the initiation of ALD growth. The obtained BN-coated carbon materials are characterized by advanced analytic transmission electron microscopy. Particular attention is paid here to the successful fabrication of 1D VdW heterostructures made of few layer hBN coated-single wall carbon nanotubes. These new 1D materials are of particular interest for applications ranging from sensing and quantum optics, to biological labeling.