Absolute densities of N and excited N2 in a N2 plasma

Atomic N and excited N2 (N) play important roles in plasma-assisted synthesis of nitride materials, such as GaN. Absolute densities of N and N were measured at the substrate plane in an inductively coupled N2 plasma in the pressure range of 10 to 200 mTorr using modulated-beam line-of-sight threshold ionization mass spectrometry. The density of N increased with increasing pressure from 2.9×1018 to 1.8×1019 m–3, while the density of N was in the range of 9.7×1017 to 2.4×1018 m–3, with a maximum at 50 mTorr. Based on the appearance potential of N at ~12 eV, we identify this excited molecule as long-lived N2 (A3) metastabl