METHYL RADICAL PRODUCTION IN A HOT FILAMENT CVD SYSTEM

The absolute concentration of methyl radicals is measured in a hot filament chemical vapor deposition system for a range of filament temperatures and input ps compositions by using ultrasensitive optical absorption with a multi-element detector at wavelengths near 216 nm. The results yield effective activation energies for CH3 production and indicate that CH3 production is dominated by the gas-phase atomic hydrogen abstraction reaction when the input gas contains CH4 and H-2. We find that passing almost-equal-to 1% tert-butyl peroxide in H-2 over a hot filament is also an efficient CH3 source, and has an activation energy similar to the activation energy for the production of CH3 from CH4.