Crystal Plane Dependent Growth of Aligned Single-Walled Carbon Nanotubes on Sapphire

Abstract

On single-crystal substrates, such as sapphire (α-Al2O3) and quartz (SiO2), single-walled carbon nanotubes (SWNTs) align along specific crystallographic axes of the crystal, indicating that the SWNT growth is influenced by the crystal surface. Here, we show that not only the orientation, but also the diameter and chirality of SWNTs are affected by the crystal plane of the sapphire substrate. The aligned SWNTs grown on the A- and R-planes of sapphire have narrower diameter distributions than randomly oriented tubes produced on the C-plane sapphire and amorphous SiO2. Photoluminescence measurements reveal a striking difference between the aligned SWNTs: near-zigzag tubes are observed on the A-plane and near-armchair tubes on the R-plane. This study shows the route for the diameter and chirality control of SWNTs by surface atomic arrangements of a single-crystal substrate.

Techniques of aligning carbon nanotubes

“…Alignment of as-grown CNTs is commonly evaluated using atomic force microscopy (AFM) [34], scanning tunneling microscopy (STM) [35] or scanning electron microscopy (SEM) [36][37][38]. Transmission electron microscopy (TEM) [39,40] is less suitable because it requires relatively complex sample preparation, which can modify the CNT arrangement.…”

“…Most popular metals used as a catalyst are Fe, Ni, Co, Mo or they allows [25]. The metal catalyst nanoparticles are often produced on the substrate using indirect processes, such as reduction of metal oxides or salts [25,[36][37][38]. The particle density and structure can be controlled by pat- terned (or masked) deposition of the metal, annealing, or by plasma etching of a metal layer.…”

“…A more delicate solution is growing the nanotubes not normal to the substrate but along its surface. Low density of the catalyst results in bending down the CNTs, and their alignment is achieved using the atomic steps on specially oriented sapphire [36][37][38] (Fig. 5) or trenched silicon [59,60] substrates.…”

Synthesis of graphene on ultra-smooth copper foils for large area flexible electronics

“…For example, the surface quality of the copper foils and the transfer printing process determine the performance and reliability of the transistors based on graphene. In this regard, the wafer scale synthesis of aligned arrays of single-walled carbon nanotubes on quartz [13] and sapphire crystals [14] is worth noting. In the case of graphene, the interesting scalable route, which is also low-cost method, is the chemical vapor deposition synthesis on copper foils [15].…”

Carbon Nanotubes as Nanosensor for Differential Electrolytic Micropotentiometry

“…Various methods have been applied for the preparation of carbon nanotubes. The most common techniques employed are: arc discharge [16] [17], laser ablation [18] and chemical vapor deposition (CVD) [19]- [21]. For the first time the deposition of CNTs on silver electrodeis reported and the resulting Ag-CNT electrodes were characterized by SEM and TEM.…”