Tunable growth of one-dimensional graphitic materials: graphene nanoribbons, carbon nanotubes, and nanoribbon/nanotube junctions

Abstract

Graphene nanoribbons (GNRs) and carbon nanotubes (CNTs), two representative one-dimensional (1D) graphitic materials, have attracted tremendous research interests due to their promising applications for future high-performance nanoelectronics. Although various methods have been developed for fabrication of GNRs or CNTs, a unified method allowing controllable synthesis of both of them, as well as their heterojunctions, which could largely benefit their nano-electronic applications, is still lacking. Here, we report on a generic growth of 1D carbon using nanoparticles catalyzed chemical vapor deposition (CVD) on atomically flat hexagonal boron nitride (h-BN) substrates. Relative ratio of the yielded GNRs and CNTs is able to be arbitrarily tuned by varying the growth temperature or feeding gas pressures. The tunability of the generic growth is quantitatively explained by a competing nucleation theory: nucleation into either GNRs or CNTs by the catalysts is determined by the free energy of their formation, which is controlled by the growth conditions. Under the guidance of the theory, we further realized growth of GNR/CNT intramolecular junctions through changing H2 partial pressure during a single growth process. Our study provides not only a universal and controllable method for growing 1D carbon nanostructures, but also a deep understanding of their growth mechanism, which would largely benefit future carbon-based electronics and optoelectronics.

Review of Carbon Nanotube Toxicity and Evaluation of Possible Implications to Occupational and Environmental Health

“…A cavity is created in the core and filled with a suitable transition metal catalyst, such as Fe or Co, that can encourage the synthesis of single-walled CNTs in the gas phase [53,54]. In the right circumstances, arc discharge may also produce the intermediate double-walled structure [55].…”

On-Surface Synthesis of Graphene Nanoribbons with Atomically Precise Structural Heterogeneities and On-Site Characterizations

“…49 Recently, a scalable single-step synthesis of micrometer-long GNRs on an insulating hexagonal boron nitride (h-BN) substrate through nanoparticle-catalyzed chemical vapor deposition was also reported. 125,140 These achievements suggest the exploration of the performance of high-quality GNR-based devices by adopting the gate-tunable STM/STS approach (Figure 4c). 141,142 The gate-tunable STM studies the electronic properties of low-dimensional systems in a field-effect transistor (FET) configuration, where the doping level can be controllably adjusted with a back gate.…”

“…In 2020, despite the low coverage and efficiency, successful on-surface synthesis of the 7-AGNRs was achieved directly on TiO 2 , a semiconducting metal oxide surface . Recently, a scalable single-step synthesis of micrometer-long GNRs on an insulating hexagonal boron nitride (h-BN) substrate through nanoparticle-catalyzed chemical vapor deposition was also reported. , These achievements suggest the exploration of the performance of high-quality GNR-based devices by adopting the gate-tunable STM/STS approach (Figure c). , The gate-tunable STM studies the electronic properties of low-dimensional systems in a field-effect transistor (FET) configuration, where the doping level can be controllably adjusted with a back gate. − This technique has been widely adopted to probe the moiré flat band physics, − low-dimensional superconductivity, , and Tomonaga–Luttinger liquids in 1D defects . Thus, one may expect to apply the gate-tunable STM/STS to explore the device behaviors − in the GNR-based FETs and single-electron transistors (SETs) and the filling-dependent correlated physics, such as the Mott transition and Wigner crystallization, , due to the correlation nature of the 1D electron systems and the existence of flat bands in GNR superlattices. ,,, …”

Collapse of carbon nanotubes due to local high-pressure from van der Waals encapsulation

“…When the growth temperature was reached, argon was replaced by methane to commence CNT growth. After a growth period of 60 min, the systems were cooled down to room temperature under a protective hydrogen and argon atmosphere 48,49 . After that, mechanically exfoliated hBN flakes on PPC film were transferred to the as-grown CNTs on SiO 2 /Si chips.…”