Effect of Barrier Layer Roughness on the Formation of Nanoparticles of the Carbon Nanotube Growth Catalyst

Abstract

This article compares TiN layers produced by electron beam evaporation (EBE) and atomic layer deposition (ALD) for the effect of barrier layer deposition technology on the formation of carbon nanotube (CNT) growth catalyst nanoparticles. The layers obtained by EBE have a roughness 1.5 times higher than the layers deposited by the ALD method (Ra=1 nm and Ra=0.6 nm). Nanoparticles formed on the surface of the EBE layer are characterized by a large average size (about 30 nm) and a 1.3 times greater dispersion of the distribution compared to nanoparticles formed on the ALD layer. TiN layers obtained by EBE are characterized by better surface wettability in comparison with ALD layers. The contact angle for catalyst nanoparticles on the surface of the EBE layer of TiN is about 30 degrees and approaches 90 degrees for ALD layers. Catalyst spreading is due to the Wenzel model. It is shown that the higher surface roughness of the EBE samples is associated with the crystallization of TiN, since the layer formation process proceeds at a higher temperature compared to the ALD process. For this reason, the use of barrier layers obtained by the ALD method is preferable for the formation of CNT growth catalyst nanoparticles on their surface. Keywords: electron beam evaporation, atomic layer deposition, roughness, wetting, catalyst nanoparticles.