Absolute densities of N and excited N2 in a N2 plasma

Atomic N and excited N-2 (N-2(*)) play important roles in plasma-assisted synthesis of nitride materials, such as GaN. Absolute densities of N and N-2(*) were measured at the substrate plane in an inductively coupled N-2 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 2.9x10(18) to 1.8x10(19) m(-3), while the density of N-2(*) was in the range of 9.7x10(17) to 2.4x10(18) m(-3), with a maximum at 50 mTorr. Based on the appearance potential of N-2(*) at similar to12 eV, we identify this excited molecule as long-lived N-2 (A(3)Sigma(u)(+)) metastable. (C) 2003 American Institute of Physics.