Microscale plasmas for metal and metal oxide nanoparticle synthesis

In this chapter, the authors discuss the novel features of microplasma sources and the recent progress that has been made in the area of nanoparticle synthesis. Low-pressure, large-scale plasmas have been successfully implemented in integrated circuit (IC) manufacturing to define micro- and nanoscale patterns, but these top-down approaches cannot be used to produce materials below approximately 10 nm in size because of limitations associated with lithography. Microscale plasmas are a special class of electrical discharges formed in geometries where at least one dimension is reduced to submillimeter length scales. Confining plasmas to small dimensions results in new physical behavior. Two general parameters that vary as the size of a plasma is decreased are the surface-to-volume ratio and the electrode spacing. Gas-phase nucleation of nanoparticles in a microplasma from vapor precursors is a natural extension of previous studies with low-pressure plasmas and larger-scale atmospheric plasma jets.