Recombination coefficients of O and N radicals on stainless steel

Surface recombination coefficients of O and N radicals in pure O-2 and N-2 plasmas, respectively, have been estimated on the stainless steel walls of a low-pressure inductively coupled plasma reactor. The recombination coeffi cients are estimated using a steady state plasma model describing the balan ce between the volume generation of the radicals from electron-impact disso ciation of the parent molecules, and the loss of the radicals due to surfac e recombination. The model uses radical and parent molecule number densitie s and the electron energy distribution function (EEDF) as input parameters. We have measured the radical number density using appearance potential mas s spectrometry. The parent neutral number density is measured using mass sp ectrometry. The EEDF is measured using a Langmuir probe. The recombination coefficient of O radicals on stainless steel walls at approximately 330 K i s estimated to be 0.17 +/- 0.02, and agrees well with previous measurements . The recombination coefficient of N radicals is estimated to be 0.07 +/- 0 .02 on stainless steel at 330 K. (C) 2000 American Institute of Physics. [S 0021-8979(00)00519-3].