ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
A thermocouple method was used to measure the concentration of hydrogen radicals at hydrogen pressures from 0.01 to 30 Torr. The concentration can be calculated from a heat balance at the thermocouple. Under low hydrogen concentration conditions, all terms in the heat balance equation must be estimated accurately. Our results for the measured absolute concentration of the hydrogen radicals at pressures below 1 Torr agreed well with the calculated concentration predicted by a model that is based on the surface dissociation probability at the hot filament and the simulation of diffusion from the filament. With increasing pressure, the hydrogen radical concentration shifted from the surface-dissociation-rate-controlled regime to the diffusion-controlled regime at the hot filament. The agreement between the heat balance at the thermocouple and that at the hot filament shows that the measurement of the hydrogen radical concentration is of the correct order. Our results show that this measurement technique could be used in studying the growth mechanisms in various deposition processes where hydrogen is a main species. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1146067
