Gas temperature dependence of coagulation onset times for nanoparticles in low pressure hydrocarbon plasmas

Abstract

Onset times for coagulation of nanoparticles in chemical reactive low pressure Ar/C2H2 and Ar/CH4 radiofrequency (rf) discharges have been measured as a function of the gas temperature while either the gas pressure or the gas density was kept constant. As a diagnostic, the phase angle between rf voltage and rf current was monitored. The results demonstrate, within the temperature range 25 °C–150 °C, that for both gases coagulation is delayed significantly (by more than a factor of 10) for increasing temperatures. These results are explained in terms of the temperature dependence of the Brownian diffusion coefficient.