Abstract
The resistance R, spectral emissivity e, and power consumption of W and Re filaments heated to 2500 °C in mixtures of CH4 or C2H2 in H2 have been measured in a series of experiments focusing on the state of the filament activity, i.e., its ability to dissociate the reactant gases. It has been found that these properties of the filaments, as well as the partial pressures of CH4 and C2H2 in the reaction chamber, depend critically on both the filament temperature and the reactant ratio, e.g., C2H2/H2. Specifically, both W and Re filaments show sharp jumps in power consumption at essentially the same temperature, signaling strong increases in filament activity and, hence, production of atomic hydrogen. These results are proposed to be due to the removal of nonreactive carbon from the surface of the filament via etching by atomic hydrogen and are consistent with the predictions of our thermodynamic model for the C–H system. Evidence for gas phase reactions is presented and the role of thermal diffusion is discussed. The emissivities of the W and Re filaments are observed to have significantly different temperature dependences which are attributed to differences in the phase diagrams for the W–C and Re–C systems. The implications of these results for hot-filament diamond CVD are discussed.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
For a useful review, see K. E. Spear, J. Am. Ceram. Soc. 72, 171 (1989).
I. J. Langmuir and G. M. J. Mackay, J. Am. Chem. Soc. 36, 1708 (1914).
M. Boudart, D. F. Ollis, and G.W. Harris, Trans. Faraday Soc. 65, 519 (1969).
S. Matsumoto, Y. Sato, M. Tsutsumi, and N. Setaka, J. Mater. Sci. 17, 3106 (1982).
F. G. Celii and J. E. Butler, Appl. Phys. Lett. 54, 1033 (1989).
M. Sommer, K. Mui, and F.W. Smith, Solid State Commun. 69, 775 (1989).
M. Sommer and F.W. Smith, to be published in High Temperature Science.
M. Sommer and F.W. Smith, Diamond, Boron Nitride, Silicon Carbide, and Related Wide Bandgap Semiconductors, J.T. Glass, R. F. Messier, and N. Fujimori (Mater, Res. Soc. Symp. Proc. 162, Pittsburgh, PA, 1989).
J. C. Batty and R. E. Stickney, J. Chem Phys. 51, 4475 (1969).
J. C. De Vos, Physica 20, 690 (1954).
O.H. Krikorian, J. H. Carpenter, and R.S. Newbury, High Temp. Sci. 1, 313 (1969).
B.T. Barnes, J. Phys. Chem. 33, 688 (1929).
F. Jansen, I. Chen, and M. A. Machonkin, J. Appl. Phys. 66, 5749 (1989).
Y. S. Toulukian and D. P. DeWitt, Thermophysical Properties of Matter (Plenum, New York, 1972), Vol. 8, p. 12.
T. D. Moustakas, Solid State Ionics 32/33, 861 (1989).
For an excellent review, see D. E. Rosner, Physico-Chemical Hydrodynamics 1, 159 (1980).
C-H. Wu, M.A. Tamor, T.J. Potter, and E.W. Kaiser, in Diamond, Boron Nitride, Silicon Carbide, and Related Wide Bandgap Semiconductors, edited by J.T. Glass, R. F. Messier, and N. Fujimori (Mater. Res. Soc. Symp. Proc. 162, Pittsburgh, PA, 1989).
P. G. Pallmer, Jr., R. L. Gordon, and M. J. Dresser, J. Appl. Phys. 51, 1798 (1980).
Constitution of Binary Alloys, First Supplement, edited by R. P. Elliot (McGraw-Hill, New York, 1965), C–Re on p.226; C–W on p.236.
P. C. Bettler, D. H. Bennum, and C. M. Case, Surf. Sci. 44, 360 (1974).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Sommer, M., Smith, F.W. Activity of tungsten and rhenium filaments in CH4/H2 and C2H2/H2 mixtures: Importance for diamond CVD. Journal of Materials Research 5, 2433–2440 (1990). https://doi.org/10.1557/JMR.1990.2433
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1557/JMR.1990.2433