Nanoparticle gas phase electrodeposition: Fundamentals, fluid dynamics, and deposition kinetics.

This communication uncovers missing fundamental elements and an expanded model of gas phase electrodeposition; a relatively new and in large parts unexplored process, which combines particle generation, transport zone and deposition zone in an interacting setup. The process enables selected area deposition of charged nanoparticles that are dispersed and transported by a carrier gas at atmospheric pressure conditions. Two key parameters have been identified: carrier gas flow rate and spark discharge power. Both parameters affect electrical current carried by charged species, nanoparticle mass, particle size and film morphology. In combination, these values enable to provide an estimate of the gas flow dependent Debye length. Together with Langmuir probe measurements of electric potential and field distribution, the transport can be described and understood. First, the transport of the charged species is dominated by the carrier gas flow. In close proximity, the transport is electric field driven. The transition region is not fixed and correlates with the electric potential profile, which is strongly dependent on the deposition rate. Considering the film morphology, the power of the discharge turns out to be the most relevant parameter. Low spark power combined with low gas flow leads to dendritic film growth. In contrast, higher spark power combined with higher gas flow produces compact layers. This contribution describes an extended model of the gas phase electrodeposition. For the first time correlations between the transport gas flow, the spark discharge power, the nanoparticle flow, the nanoparticle mass and the film morphology are shown. The transport properties in the gas phase are strongly dependent on the transport gas flow, which represents the biggest difference in the description of the transport equation compared to classic electroplating. Image 1 • This article reports materials, methods and technology to increase the understanding of the in large parts unexplored gas phase electrodeposition process. • To understand the expanded model, two key parameters have been identified; the carrier gas flow rate and the spark discharge plasma power. • Both parameters affect measurable quantities such as the electrical current carried by the charged nanoparticles and gas ions, the nanoparticle mass, particle size and film morphology. • Particle generation rate, ratio between charged gas ions and charged nanoparticles are subsequently derived. • Together with Langmuir probe measurements of the electric potential and field distribution the transport can be described and understood. [ABSTRACT FROM AUTHOR]