Jong Sun Yun and Dong-Wha Park

Dept. of Chemical Engineering, Inha University
253 Yonghyun-dong, Nam-gu, Inchon 402-751, Korea
dwpark@munhak.inha.ac.kr

Diamond film was synthesized on molybdenum substrate by chemical vapor deposition of methane and hydrogen gas using the DC plasma jet at atmospheric pressure. The experiments were conducted by changing of the CH4/H2 ratios (2-7%), substrate temperatures (800-1200 C) and deposition times (5min-2hrs). Scanning electron microscopy, x-ray diffraction, and Raman spectroscopy were used to assess film morphology and carbon phase.

At CH4/H2 ratio of 4% and substrate temperature of 970 C, the film had a good crystallinity with cubo-octahedral shaped facets. The films on (111) faces were achieved at relatively low CH4/H2 ratios (2.3%). The films on (100) faces were grown at high substrate temperatures (1100-1200 C). For growth condition that deviated from the optimum condition, twins and secondary ledge growth were the predominant morphological features.

The difference of the film morphology between seeded substrate with diamond paste pretreatment and native substrate without diamond paste pretreatment was considered. The thickness of diamond film was estimated by changing of the deposition time under the optimum condition. For example, the thickness of diamond film is almost 100 for deposition time of 30 min.