The Mo substrate with Zr interlayer,namely composite substrate,was employed to solve the problem of crack formation in the freestanding diamond film deposition.Freestanding diamond films deposited on the composite substrates by the direct current arc plasma jet chemical vapor deposition（CVD） method were investigated with scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy （XPS）,X-ray diffraction（XRD）,and Raman spectroscopy.In addition,the stress distribution during the large area freestanding diamond film deposition on the composite substrate was analyzed based on the finite element model ANSYS.The results reveal that Zr interlayer can be easily destroyed during the post-deposition cooling process,which is helpful for stress release and crack avoiding in diamond films.
Zheng Liu Cheng-ming Li Liang-xian Chen Li-mei Wang Li-fu Hei Fan-xiu Lu
Thermal stress in large area free-standing diamond films was remarkable during the post-deposition cooling of direct current （DC） arc plasma jet chemical vapor deposition （CVD） process.In this research,the stress release caused by delamination of Cr interlayer was of great importance to ensure the integrity of free-standing diamond film.The effects of Cr interlayer on Mo substrate,namely composite substrate,on thermal stress were investigated.Thermo-mechanical coupling analysis of the thermal stress was applied by finite element analysis （FEA） using ANSYS code.It was found that the interlayer could be destroyed first by the large thermal stress,and then the stress could be released and the probability of diamond film crack initiation would be reduced.The stress concentration at the bent edge of diamond film was also discussed.In addition,diamond films deposited on Mo substrates with and without Cr interlayer were prepared by DC arc plasma jet CVD system and experimental measurements were used to characterize these films.It was found that composite substrate could be an effective method of growing free-standing crack-free diamond films by DC arc plasma jet CVD system when there is no special requirement to the film strength.
Zheng Liu,Liangxian Chen,Chengming Li,Lifu Hei,Jianhua Song,Guangchao Chen,Weizhong Tang and Fanxiu Lv School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China
