Effects of hydrogenated amorphous carbon interlayer on diamond nucleation
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Effects of hydrogenated amorphous carbon interlayer on diamond nucleation W. S. Yang, T. S. Kim,a) and Jung Ho Jeb) Department of Materials Science and Engineering, Pohang University of Science & Technology, San 31, Hoyja Dong, Pohang, Kyungbuk 790-784, Republic of Korea (Received 10 December 1996; accepted 30 April 1997)
Diamond was deposited at 850 ±C by microwave plasma chemical vapor deposition (CVD) on the interlayers with various intensity ratios (IDyIG ) of the D band (,1400 cm21 ) to the G band (,1570 cm21 ) in the Raman spectra. Diamond could be grown only on the interlayers with higher IDyIG (>1.95), and Nd was slightly increased to 3 3 106ycm2 with ID yIG . The predeposition at 350 ±C, which decreased the full-width at half-maximum of the broad D band, further increased Nd to 5 3 107ycm2 . With ˚ Pt overlayer on the interlayer, Nd was much more enhanced to 8 3 107ycm2 . 300 A We suggest the sp 3 bonded carbon clusters within the interlayer contribute to diamond nucleation, but they should be survived against atomic hydrogen etching during diamond deposition by increasing the sp 3ysp 2 ratio, by increasing the degree in clustering, or by protecting them with overlayer.
I. INTRODUCTION
The growth of diamond film by chemical vapor deposition (CVD) is a current worldwide topic of great attention due to its promising applications. One critical issue in realizing most of these applications is a sound understanding of the nucleation mechanism on foreign substrates.1,2 The nucleation density of diamond (Nd ) is generally very low on foreign substrates without the substrate pretreatment prior to diamond deposition.1,2 Various pretreatments have been developed to enhance Nd : mechanical abrasion,3–8 bias enhanced nucleation (BEN),2,9,10 interlayer deposition of various carbonaceous11–23 or noncarbonaceous materials,12,23–27 ion beam irradiation,28,29 etc. In mechanical abrasion, substrate surface was scratched or ultrasonically abraded with diamond powder3–5 or other abrasives such as SiC,6–8 c-BN,7,8 etc. In BEN, a negative dc bias voltage was applied to the substrate in a CH4 –H2 plasma prior to diamond deposition. In interlayer deposition, besides noncarbonaceous materials such as BN,12,23 Fe,24,25 or Fe–Si,26,27 the following carbonaceous materials have been tried: hydrogenated amorphous carbon (a-C : H),11–15 nonhydrogenated amorphous carbon (a-C),12,16–19 graphitic carbon,20,21 C60 ,18,22 SiC,12,23 and hydrocarbon oil.16 Here it is noteworthy that although carbonaceous materials were not deposited as an interlayer, an amora)
Present address: Laboratory, Precision Component Division, Samsung Display Devices Co., Ltd. 575, Shin-Ri, Taean-Eub, HwasungKun, Kyungki-Do 445-970, Korea. b) Corresponding author; e-mail: [email protected] 596
http://journals.cambridge.org
J. Mater. Res., Vol. 13, No. 3, Mar 1998
Downloaded: 18 Mar 2015
phous carbonlayer could be formed during diamond deposition even on the substrates pretreated by diamond abrasion,30,31 BEN process
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