(Invited) Microplasma Jet Deposition of Nanostructured Materials

Abstract

The ability to synthesize functional nanoscale materials, as well as integrate them into larger systems, is fundamental to the development of next-generation micro- and optoelectronic devices, sensors, and energy harvesting and storage technologies. Toward this goal, we have developed a versatile, plasma spray-like deposition technique, based on flow-through micro-hollow cathode discharges at 10-100 Torr (microplasma jets), that can deposit nanoparticles, dense layers, and structured thin films of crystalline materials on virtually any surface. A supersonic DC microplasma jet is seeded with organometallic precursors under reducing or oxidizing conditions to create a directed flux of growth species (e.g., atoms, ions, clusters, and/or nanoparticles) that are subsequently 'spray-deposited' onto the surface of interest. A remote anode is used to complete the plasma circuit, allowing deposition on conductors, insulators, polymers, fibers, and lithographic patterns at room temperature in a conformal fashion. A diverse range of nanostructured materials, e.g., metals (Cu, Ni, Pd), oxides (CuO, ZnO, SnO 2 , NiO, Fe 2 O 3 , Co x O y ), doped oxides (Fe x Ni 1-x O), spinels (NiFe 2 O 4 ), and sulfides (CuS), with different morphologies (nanoparticles, dense columnar films, or hierarchical nanostructures, etc.) can be realized with the technique. The talk will specifically focus on microplasma jet operation, growth dynamics, and applications of microplasma-deposited films including solar cell, battery and supercap electrodes, photo(electro)catalysts, and biphasic nanogranular materials for magnetic exchange bias studies.