Charge and charging of nanoparticles in a SiH4 rf-plasma.

Plasma-produced nanoparticles are of interest for many applications. They have very specific properties that can vary greatly from those in the atomic and bulk materials, including thermodynamic properties, such as a reduced melting temperature, and optical properties, such as blue-shifted blackbody radiation. Since a plasma is dominated by free electrons, charge related properties, like a reduced work function for electron attachment and increased work function for photo ionization, are of major importance. In situ detection of nanoparticles inside a plasma is difficult. Hence, indirect methods including changes in optical emission, plasma voltage and currents are used to study particle growth. Here, electron density measurements in the plasma are presented using an ultrafast microwave resonance technique (time resolution below 1 micros). This technique allows studying the charge and charging kinetics of nanoparticles within the initial milliseconds of their growth.