Application of NiO deposited by atomic layer deposition for carbon nanotubes catalytic growth

Carbon nanotubes (CNTs) are a unique object for various kinds of electronic devices. At the same time, an important task remains the development of catalytic structure synthesis methods for repeatability and uniform growth of CNTs. One of such methods is atomic layer deposition (ALD). The article considers the effect of the initial NiO layer thickness obtained by the ALD method on the growth of carbon nanotubes array. Deposition of the CNTs was carried out by the direct current plasma-enhanced chemical vapor deposition method using a direct current discharge in an acetylene and ammonia at 680 °C. Before CNT deposition, the NiO film was reduced to metallic nickel in an ammonia atmosphere at 680 °C. Samples were studied by scanning and transmission electron microscopy. As a result, the thickness of the initial NiO film for intensive CNT growth was in the range of 3.5 to 3.9 nm. CNTs had a “multi-walled” structure and consisted of 15 ± 5 graphene layers. The density of the tubes was about 7.5 ± 0.2 × 10¹⁰ cm⁻², and the length was 6–7.5 µm.