Template Assisted Growth of 1D Heterostructures

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This project aims to synthesize 1D vdW bilayers and heterostructures with defined moiré pattern (controlled by selection of chirality) of the constituent walls. Structurally well-defined single-walled carbon nanotubes (SWCNTs) will be used to template the growth of inner- and outer-walls of either carbon or boron nitride. In work package 1 (WP1), a process known as aqueous two phases extraction (ATPE) will be used to prepare mono-chiral SWCNTs, including metallic, semiconducting and left and right-handed species, with a diameter of 1.4 – 1.5 nm. These will be filled with C60 to form a peapod structure and converted to a double-walled carbon nanotube (DWCNT) at high temperature. Geometrical constraints provided by the outer-wall will reduce the number of possible inner-walls during growth and it is predicted that the outer- wall may even favor the formation of a single chiral inner-wall. In WP2 a complementary process using the encapsulation of boron precursors will be used to create a 1D boron nitride/carbon heterostructure. Alternatively, the external surface of the carbon nanotube will be used to template the direct growth of an outer-wall of boron nitride, and chirality controlled DWCNTs from WP1 will be converted to boron nitride. In this way, new insights will be gained into the role of the inner/outer-wall in defining the atomic structure of its counterpart and a study of controllable moiré patterns in 1D nanostructures will be enabled. This project will investigate the optical and electronic coupling between structurally defined walls by measuring spectral shifts relative to single walled species in photoluminescence and Raman spectroscopy and by making electronic measurements at low temperature to probe new phenomena such as superconductivity.