The deposition of oriented diamond film by hot-filament chemical vapor deposition with separate reactant gas
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The deposition of oriented diamond film by hot-filament chemical vapor deposition with separate reactant gas G.C. Chen,a) C. Sun, R.F. Huang, and L.S. Wen Institute of Metal Research, Academia Sinica, Shenyang, People’s Republic of China
D.Y. Jiang, and X.Z. Yao Institute of Physics, Academia Sinica, Beijing, People’s Republic of China (Received 8 December 1997; accepted 13 May 1999)
A (110)-oriented diamond film was deposited by hot filament chemical vapor deposition with H2 and CH4 separately introduced into the reactive zone. The film with a degree of orientation I(220)/I(111) of more than 200% and deposition rate of 2–3 m/h was obtained for a deposition time of 17 h. The long deposition time enlarged the grain size and enhanced the degree of orientation, but too long a deposition time resulted in random growth. The temperature field was measured and also calculated using a simple model. Both results showed that a temperature field existed with varied gradients along the normal of substrate surface. The (110)-oriented diamond film was deposited in the zone with negative temperature gradient. The change in orientation occurring for long deposition times was ascribed to the change of temperature gradient. The deposition of diamond film is a rapidly expanding technology with enormous economic potential. An oriented diamond film is required for potential applications in optics and electronics.1,2 This kind of film is usually described by the term I(hkl)/I(111), in which I is the intensity of x-ray diffraction peak and (hkl) is the index of the crystal surface. In oriented film, there are three domain kinds of morphologies: square, triangle, and cubooctahedron.3 Wild4 and Clausing5 have described how the relative growth velocities in 〈100〉 and 〈111〉 direction (i.e., ␣ ⳱ 〈100〉/〈111〉) determine crystal shape and film orientation. Wild also showed (110)-oriented film with triangular morphology.4 To develop the deposition of oriented diamond film, it is important to control the experiment condition without upsetting ␣.6 Several methods were used to deposit the oriented film, such as microwave chemical vapor deposition (CVD),7 direct current plasma jet,8 combustion flame,9 and hot-filament CVD (HFCVD).10 The influence of the experimental condition, including the ratio of hydrogen and hydrocarbon,7 temperature and chemistry species,11 and substrate condition,12 on the morphology of oriented diamond film was discussed based on these methods. All these discussions were set in a similar temperature field, namely positive temperature gradient from substrate to gas nutrient.13,14 In this kind of temperature field, however, long deposition times, even several tens of hours,10
a)
Address all correspondence to this author. Present address: 106 Group, Institute of Physics, Beijing, People’s Republic of China. e-mail: [email protected]
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http://journals.cambridge.org
J. Mater. Res., Vol. 14, No. 8, Aug 1999 Downloaded: 24 Apr 2015
would be needed because of deposition rates b
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