ISSN:
1572-8986
Keywords:
Diamond synthesis
;
pulsed microwave discharge
;
optical emission spectroscopy
;
actinometry
;
atomic hydrogen
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Technology
Notes:
Abstract Pulsing of a microwave discharge is a promising new technique to improve the control of the diamond deposition process. A small amount of argon (5% Ar) was added to the usual feed stock (0.5% methane in hydrogen) to act as an actinometer. Plasma emission was observed during the pulse on-times for pulse repetition rates from 50 Hz to 10 kHz by time-resolved optical spectroscopy. Determined relaxation time constants for atomic hydrogen are on the order of 1 ms. Thus, the atomic hydrogen concentrations do not vary very much at a pulse repetition rate of 20 kHz, whereas at 50 Hz the radical concentrations vary between a saturation value and zero. The saturation value of atomic hydrogen increases with increasing peak power, but mean values are generally lower as in the continuous wave mode with the same average power and decrease with decreasing duty cycles and pulse repetition rates. The results are consistent with deposition experiments.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01465742
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