Growth of textured diamond films on Si(100) by C 2 H 2 /O 2 flame method
- PDF / 1,061,701 Bytes
- 3 Pages / 593.28 x 841.68 pts Page_size
- 7 Downloads / 189 Views
Z.C.Feng Department of Physics, Emory University, Atlanta, Georgia 30322 (Received 30 March 1990; accepted 27 June 1990)
Highly textured diamond thin films with (111) orientation have been successfully grown on the single crystal silicon (100) substrates by the flame method using the premixed acetylene and oxygen gas. Scanning electron microscopy (SEM), x-ray diffraction, and Raman spectroscopy studies have shown the formation of uniform diamond films with the full coverage of the deposition area on the Si substrates. An approach which leads to growing diamond films with very low graphite and/or amorphous carbon contaminations is described.
I. INTRODUCTION
The synthesis of diamond films in low temperature and low vacuum environment is very attractive because of its great potential for various applications, including microelectronics, tribology, and optics.1'2 The low pressure and low temperature techniques, such as thermal chemical vapor deposition (CVD),3"5 microwave plasma CVD,6"8 and DC plasma CVD,9 are all based on the decomposition of hydrocarbon mixtures with or without hydrogen gas. However, the diamond films synthesized by these methods typically have problems of low growth rate, nonepitaxial growth, and hydrogen contamination. The combustion flame method10"12 developed recently has unique advantages of economy, easy setup, and higher growth rate in comparison to the conventional CVD techniques. In this paper, we report the successful growth of partially textured high-quality diamond films on silicon (100) by using the flame method. It has been determined that the luminous boundary outside the blue-green reacting zone of the premixed C 2 H 2 /O 2 flame determines the diamond crystals formation in air when the C 2 H 2 /O 2 ratio is near one. II. EXPERIMENTAL
Pure acetylene and oxygen gases were used as the reactants. The gas flows were controlled by two separate gas flowmeters to adjust the proper C 2 H 2 /O 2 ratio. The gases were premixed just before the flame torch. Polished single crystal silicon (100) wafers seeded with 1 ^tm diamond powder were used as the substrates. The substrate was placed on a water-cooled copper susceptor. Due to the existence of large temperature gradients a) Address
correspondence to this author.
2334
http://journals.cambridge.org
J. Mater. Res., Vol. 5, No. 11, Nov 1990
Downloaded: 08 Apr 2015
in the deposition zone, the temperature measurements on the substrate surface and in the flame were complicated. We estimated the substrate temperature to be in the range of 800-900 °C by using an optical pyrometer. Combustion flames have typically three distinct layers: the outer diffusion zone with violet color from the C-H band radiation, the middle reaction zone with bluegreen color due to the C2 band radiation, and the bright yellow inner cone.13 Our early results showed that the diamond particles always formed at the outer ring of the deposited area when the silicon substrates were placed only in the blue-green carbon zone and when the flame was acetylene-rich. Under this
Data Loading...
