VELOCITY DISTRIBUTIONS OF NH2 RADICALS IN AN NH3 PLASMA MOLECULAR-BEAM

Using spatially and temporally resolved LIF wr have measured the veloc ity distributions of NH2 molecules in an effusive NH, plasma molecular beam as a function of applied rf plasma power. Monte Carlo simulation methods are used to model spatial profiles of radicals in the molecul ar beam, The model assumes a. Gaussian distribution and calculates tim e dependent changes in the profiles using Maxwell-Boltzmann distributi ons. The translational temperature increases with rf power, from 512 /- 8 K at 25 W to 664 +/- 35 It at 150 W. Preliminary data on velocity profiles fur NH2 radicals scattered from a 300 K Si substrate are pre sented. (C) 1997 Elsevier Science B.V.