研究生: |
洪傳智 Chuan-Chic Hung |
---|---|
論文名稱: |
在不同超奈米鑽石薄膜核層上成長微米晶鑽石薄膜之特性研究 Study on characteristics of microcrystalline diamond thin films deposited on different nuclear layers of ultrananocrystalline diamond thin films |
指導教授: |
鄭秀鳳
Cheng, Hsiu-Fung |
學位類別: |
碩士 Master |
系所名稱: |
物理學系 Department of Physics |
論文出版年: | 2011 |
畢業學年度: | 99 |
語文別: | 中文 |
論文頁數: | 138 |
中文關鍵詞: | 微波電漿輔助化學汽相沉積法 、超奈米晶鑽石薄膜 、穿隧式電子顯微鏡 |
英文關鍵詞: | MPECVD, UNCD, TEM |
論文種類: | 學術論文 |
相關次數: | 點閱:195 下載:18 |
分享至: |
查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報 |
鑽石具有優異之物理、化學、機械性質,所以鑽石膜之合成為目前熱門之研究課題,鑽石薄膜具有好的電子場發射特性,適於製造場發射器。而化學汽相沉積法(Chemical Vapor Deposition, CVD)已被應用於成長鑽石薄膜。在這項研究中,我們使用微波電漿輔助化學汽相沉積法(Microwave Plasma Enhanced Chemical Vapor Deposition, MPECVD)成長鑽石薄膜,探討在不同超奈米晶鑽石薄膜上成長微米晶鑽石薄膜的生長機制與微結構特性研究。在獲得好品質鑽石薄膜,我們使用拉曼光譜儀,場發射掃描電子顯微鏡(SEM)與電子場發射設備 (EFE)與可見光發射光譜儀(OES),穿隧式電子顯微鏡(TEM)分析鑽石薄膜結構特性,並對其成長機制進行探討。在甲烷/氬氣電漿中可成長2-10 nm的超奈米鑽石結構。在甲烷/氬氣電漿中加入氫氣成長超奈米鑽石薄膜,隨時間與氫氣流量增加,大晶粒比例增加,起始電場值增加;然後,接著進一步在改變H2含量與時間所鍍成之不同超奈米鑽石薄膜核層上,再固定最佳化的相同鍍膜參數來成長微米晶鑽石薄膜,發現所成長MCD/UNCD1薄膜90 min,在電子場發射中起始電場值可自19.00 V/μm下降到10.50 V/μm,可能由於MCD/UNCD晶粒上和周圍形成奈米鑽石晶粒,導致晶界密度提高。
Diamond has excellent physical, chemical, and mechanical properties, etc.. So, the syntheses of diamond films are the hot research topics. The diamond films have good field emission properties and are suitable for the application to the field emission devices. The chemical vapor deposition (CVD) has been applied to grow diamond films. In this study, in order to understand the growth mechanism and the microstructure characteristics, we used microwave plasma enhanced chemical vapor deposition (MPECVD) technique to grow different ultrananocrystalline diamond (UNCD) thin films as nuclear layers for fabricating microcrystalline diamond (MCD) thin films. In order to investigate the as deposited good quality diamond thin films, we used Raman spectroscopy, field emission scanning electron microscopy (SEM), electron field emission (EFE) technique, optical emission spectroscopy (OES), and transmission electron microscopy (TEM) to analyze characteristics of MCD/UNCD thin films, and discuss their growth mechanism. The UNCD structure of ultra-nanoparticles with grain size 2–10 nm can be grown in the methane / argon plasma. The growth and properties of UNCD thin films have been changed profoundly by adding hydrogen. The increase of hydrogen flow rate and deposition time has enhanced the proportion of large diamond grains. This leads to the increment of turn-on electric field. However the decrease from 19.00 V/μm to 10.50 V/μm for turn-on electric field of microcrystalline diamond thin films grown on various as deposited nuclear layers of ultrananocrystalline diamond thin films has been observed. This is presumably ascribed to the increase in the grain boundary density of nanocrystalline diamonds formed on or around the grains of MCD/UNCD .
[1]. J. E. Field, “The Properties of Diamonds,” (Academic, London, 1979).
[2]. H. Liu and D. S. Dandy, “Diamond Chemical Vapor Deposition: Nucleation and Early Growth Stages,” Noyes (1995).
[3]. P. Kulkarni, L. M. Porter, F. A. M. Koeck, Y. J. Tang, and R. J. Nemanich, “Electrical and photoelectrical characterization of undoped and S-doped nanocrystalline diamond films,” J. Appl. Phys. Vol. 103, 0849051–0849058 (2008).
[4]. M. Shamsa, S. Ghosh, I. Calizo, V. Ralchenko, A. Popovich, and A. A. Balandin, “Thermal conductivity of nitrogenated ultrananocrystalline diamond films on silicon,” J. Appl. Phys. Vol. 103, 0835381–0835388 (2008).
[5]. X. Xiao, J. Birrell, J. E. Gerbi, O. Auciello, and J. A. Carlisle, “Low temperature growth of ultrananocrystalline diamond,” J. Appl. Phys. Vol. 96, 2232–2239 (2004).
[6]. Li-Ju Chen, Nyan-Hwa Tai, Chi-Young Lee, and I-Nan. Lin, “Effects of pretreatment processes on improving the formation of ultrananocrystalline diamond,” J. Appl. Phys. Vol. 101, 06430801–06430816 (2007).
[7]. K. Wu, E.G. Wang, Z.X. Cao, Z.L. Wang, and X. Jiang, “Microstructure and its effect on field electron emission of grain-size-controlled nanocrystalline diamond films,” J. Appl. Phys. Vol. 88, 2967–2974 (2000).
[8]. Maki A. Angadi, Taku Watanabe, Arun Bodapati, Xingcheng Xiao, and Simon R. Phillpot, “Thermal transport and grain boundary conductance in ultrananocrystalline diamond thin films,” J. Appl. Phys. Vol. 99, 1143011–1143016 (2006).
[9]. D.M. Gruen, “Nanocrystalline diamond films,” Annu. Rev. Mater. Sci. Vol. 29, 211–259 (1999).
[10]. J. A. Carlisle and O. Auciello, “Ultrananocrystalline diamond,” Electrochem. Soc. Interface, 28–31 (2003).
[11]. F. Mubarok, J.M. Carrapichano, F.A. Almeida, A.J.S. Fernandes, and R.F. Silva, “ Enhanced sealing performance with CVD nanocrystalline diamond films in self-mated mechanical seals,” Diamond Relat. Mater. Vol. 17, 1132–1136 (2008).
[12]. A. Lavoisier, “Elements of Chemistry,” Dover Publications (1772).
[13]. Y. Tzeng, M. Yoshikawa, M. Murakawa, and Feldman, “The Applications of Diamond Films and Related Materials,” eds, Elsevier, New York (1991).
[14]. P. W. Bridgman, “Synthetic diamonds,” Scient. Am. Vol. 193, 42 (1955).
[15]. W. G. Eversole and U.S. Patent No. 3,030,188 (1962).
[16]. J. C. Angus, H. A. Will, and W. S. Stanko, “Growth of diamond seed crystals by vapor deposition,” J. Appl. Phys. Vol. 39, 2915–2922 (1968).
[17]. B. V. Spitsyn, L. L. Bouilov, and B. V. Derjaguin, “Vapor growth of diamond on diamond and other surfaces,” Journal of Crystal Growth Vol. 52, 219–226 (1981).
[18]. Peter K. Bachmann, Dieter Leers, and Hans Lydtin, “Towards a general concept of diamond chemical vapour deposition,” Diamond Relat. Mater. Vol. 1, 1–12 (1991).
[19]. G. Balestrino, M. Marinelli, E. Milani, A. Paoletti, I. Pinter, and A. Tebano, “Growth of diamond films: general correlation between film morphology and plasma emission spectra,” Appl. Phys. Lett. Vol. 62, 879–881 (1993).
[20]. Y. Mitsuda, K. Tanaka, and T. Yoshida, J., “In situ emission and mass spectroscopic measurement of chemical species responsible for diamond growth in a microwave plasma jet,” J. Appl. Phys. Vol. 67, 3604–3608 (1990).
[21]. C. J. Chu, R. H. Hauge, J. L. Margrave, and M. P. D'Evelyn, “Growth kinetics of (100), (110), and (111) homoepitaxial diamond films,” Appl. Phys. Lett. Vol. 61, 1393–1395 (1992).
[22]. Stephen J. Harris, “Gas-phase kinetics during diamond growth: CH4 as-growth species,” J. Appl. Phys. Vol. 65, 3044–3048 (1989).
[23]. Chao Liu, Xingcheng Xiao, Hsien-Hau Wang, Orlando Auciello, and John A. Carlisle , “Electron paramagnetic resonance study of hydrogen-incorporated ultrananocrystalline diamond thin films,” J. Appl. Phys. Vol. 101, 1239241–1239246 (2007).
[24]. Wiora, M. Bruhne, K. Floter, A. Gluche, P. Willey, T.M. Kucheyev, S.O. Van Buuren, A.W., and Fecht, H.J. “Grain size dependent mechanical properties of nanocrystalline diamond films grown by hot-filament CVD,” Diamond Relat. Mater. Vol. 18, 927–930 (2009).
[25]. Ray, S.J. and Hieftje, G.M. “Microwave plasma torch — atmospheric-sampling glow discharge modulated tandem source for the sequential acquisition of molecular fragmentation and atomic mass spectra ,” Analytica Chimica Acta Vol. 445 (1), 35–45 (2001).
[26]. A. T. Sowers, B. L. Ward, S. L. Englih, and R. J. Nemanich, “Field emission properties of nitrogen-doped diamond films,” J. Appl. Phys. Vol. 86, 3973–3982 (1999).
[27]. K. H. Chen, D. M. Bhusari, J. R. Yang, S. T. Lin, T. Y. Wang, and L. C. Chen,“Highly transparent nano-crystalline diamond films via substrate pretreament and methane fraction optimization,” Thin Solid Films Vol. 332, 34–39 (1998).
[28]. Nevin N. Naguib, Jeffrey W. Elam, James Birrell, Jian Wang, David S. Grierson, and Bernd Kabius, “Enhanced nucleation, smoothness and conformality of ultrananocrystalline diamond (UNCD) ultrathin films via tungsten interlayers,” Chemical Physics Letters Vol. 430, 345–350 (2006).
[29]. J. Birrell, J. A. Carlisle, O. Auciello, D. M. Gruen, and J. M. Gibson, “Morphology and electronic structure in nitrogen-doped ultrananocrystalline diamond,” Appl. Phys. Lett. Vol. 81 (12), 2235–2237 (2002).
[30]. S. Jiao, A. Sumant, M. A.Kirk, D. M. Gruen, A. R. Krauss, and O. Auciello, “Microstructure of ultrananocrystalline diamond films grown by microwave Ar–CH4 plasma chemical vapor deposition with or without added H2,” J. Appl. Phys. Vol. 90, 118–122 (2001).
[31]. X. Xiao, J. Birrell, J. E. Gerbi, O. Auciello, and J. A. Carlisle, “Low temperature growth of ultrananocrystalline diamond,” J. Appl. Phys. Vol. 96 (4), 2232–2239 (2004).
[32]. D. A. Homer, L. A. Curtiss, and D. M. Gruen, “A theoretical study of the energetics of insertion of dicarbon (C2) and vinylidene into methane C-H bonds,” Chemical Physics Letters Vol. 233, 243–248 (1995).
[33]. K. Subramaniana, W. P. Kanga, J. L. Davidsona, R. S. Takalkara, B. K. Choia, M. Howella, and D.V. Kerns, “Enhanced electron field emission from micropatterned pyramidal diamond tips incorporating CH4/H2/N2 plasma-deposited nanodiamond,” Diamond Relat. Mater. Vol. 15, 1126–1131 (2006).
[34]. Ku, T. K. Yang, C. D. Tarntair, F. G. Wang, C. C. Cheng, H. C. Chen, S. H. She, N. J. Hsieh, and I. J. Hsieh, “Enhanced electron emission from phosphorus- and boron-doped diamond-clad Si field emitter arrays,” Thin Solid Films Vol. 290, 176–180 (1996).
[35]. Yongde Xia, Gavin S. Walker, David M. Grant, Mokaya, and Robert , “Hydrogen storage in high surface area carbons: experimental demonstration of the effects of nitrogen doping,” Journal of the American Chemical Society Vol. 131, 16493–16499 (2009).
[36]. H. Yoshikawa, C. Morel, and Y. Koga, “Synthesis of nanocrystalline diamond films using microwave plasma CVD,” Diamond Relat. Mater. Vol. 10, 1588–1591 (2001).
[37]. J. Lee, R. W. Collins, R. Messier, and Y. E. Strausser, “Low temperature plasma process based on CO-rich CO/H2 mixtures for high rate diamond film deposition,” Appl. Phys. Lett. Vol. 70, 1527–1529 (1997).
[38]. N. Jiang, K. Sugimoto, K. Nishimura, Y. Shintani, and A. Hiraki, “Synthesis and structural study of nano/micro diamond overlayer films,” Journal of Crystal Growth Vol. 242, 362–366 (2002).
[39]. T. Sharda, M. Vmeno, T. Soga, and T. Jimbo, “Growth of nanocrystalline diamond films by biased enhanced microwave plasma chemical vapor deposition: A different regime of growth,” Appl. Phys. Lett. Vol. 77 (26), 4304–4306 (2000).
[40]. W. Zhu, G P. Kochanski, and S. Jin, “Low-field emission from undoped nanostructured diamond,” Science Vol. 282, 1471–1473 (1998).
[41]. A. Göhl, A. N. Alimova, T. Habennann, A. L. Mescheryakova, and G Huller,“Integral and local field emission analyses of nanodiamond coating for power applications,” J. Vac. Sci. Technol. B, Vol. 17, 670–673 (1999).
[42]. J. E. Green, S. A. Barnett, J. E. Sundgren, and A. Rockett, “Plasma-Surface Interactions and Processing of Materials: Proceedings,” 28–31(1990).
[43]. X. Jiang, C. P. Klages, R. Zachai, M. Hartweg, and H. J. Fusser, “Epitaxial diamond thin films on (001) silicon substrate,” Appl. Phys. Lett. Vol. 62, 3438–3440 (1993).
[44]. S. Iijima, Y. Aikawa, and K. Baba, “Early formation of chemical vapor deposition diamond films,” Appl. Phys. Lett. Vol. 57 (25), 2646–2648 (1990).
[45]. Zhidan Li, Long Wang, Tetsuya Suzuki, and Pirouz, “Orientation relationship between chemical vapor deposited diamond and graphite substrates,” J. Appl. Phys. Vol. 73(2), 711–715 (1993).
[46]. D. N. Belton, S. J. Harris, S. J. Schmieg, A. M. Wiener, and T. A. Perry, “In situ characteristic of diamond nucleation and growth,” Appl. Phys. Lett. Vol. 54 (5), 416–417 (1989).
[47]. N. Jiang, B. W. Sun, Z. Zhang, and Z. Lin, “Nucleation and initial growth of diamond film on Si substrate,” Journal of Materials Research Vol. 9 (10), 2695–2702 (1994).
[48]. W. L. Wang, K. J. Liao, L. Fang, J. Esteve, and M. C. Polo, “Analysis of diamond nucleation on molybdenum by biased hot filament chemical vapor deposition,” Diamond Relat. Mater. Vol. 10, 383–387 (2001).
[49]. S. Yugo, T. Kanai, T. Kimura, and T. Muto, “Generation of diamond nuclei by electric field in plasma chemical vapor deposition,” Appl. Phys. Lett. Vol. 58 (10), 1036–1038 (1991).
[50]. B. R. Stoner, G. H. M. Ma, S. D. Wolter, and J. T. Glass, “Characterization of bias-enhanced nucleation of diamond on silicon by invacuo surface analysis and transmission electron microscopy,” Phys. Rev. (B) Vol. 45, 11067–11084 (1991).
[51]. J. Gerber, S. Sattel, H. Ehrhardt, J. Robertson, P. Wurzinger, and P. Pongratz, “Investigation of bias enhanced nucleation of diamond on silicon,” J. Appl. Phys. Vol. 79 (8), 4388–4396 (1996).
[52]. P. Reinke and P. Oelhafen, “Photoelectron spectroscopic investigation of the bias-enhanced nucleation of polycrystalline diamond films,” Phys. Rev. (B) Vol. 56 (4), 2183–2190 (1997).
[53]. R. Stöckel, K. Janischowsky, S. Rohmfeld, J. Ristein, M. Hundhausen, and L. Ley, “Growth of diamond on silicon during the bias pretreatment in chemical vapour deposition of polycristalline diamond films,” J. Appl. Phys. Vol. 79, 768–775 (1996).
[54]. R. Stöckel, M. Stammler, K. Janischowsky, and L. Ley, “Diamond nucleation under bias conditions,” J. Appl. Phys. Vol. 83, 531–539 (1998).
[55]. J. Robertson, J. Gerber, S. Sattel, M. Weiler, K. Jung, and H. Ehrhardt, “Mechanism of bias-enhanced nucleation of diamond on Si,” Appl. Phys. Lett. Vol. 66 (24), 3287–3289 (1995).
[56]. S. P. McGinnis, M. A. Kelly, and S. B. Hagstrom, “Evidence of an energetic ion bombardment mechanism for bias-enhanced nucleation of diamond,” Appl. Phys. Lett. Vol. 66 (23), 3117–3119 (1995).
[57]. L. J. Huang, I. Bello, W. M. Lau, S. T. Lee, P. A. Stevens, and B. D. DeVries, “Synchrotron radiation x-ray absorption of ion bombardment induced defects on diamond(100) ,” J. Appl. Phys. Vol. 76 (11), 7483–7486 (1994).
[58]. S. Barrat, S. Saada, I. Dieguez, and E. Bauer-Grosse, “Diamond deposition by chemical vapor deposition process: study of the bias enhanced nucleation step,” J. Appl. Phys. Vol. 84 (4), 1870–1880 (1998).
[59]. Debabrata Pradhan, Li-Ju Chen, Yen-Chih Lee, Chi-Young Lee, Nyan-Hwa Tai, and I-Nan Lin, “Effect of titanium metal in the prenucleation of ultrananocrystalline diamond film growth at low substrate temperature,” Diamond Relat. Mater. Vol. 15, 1779–1783 (2006).
[60]. J. H. Je and G. Y. Lee, “Microstructures of diamond films deposited on (100) silicon wafer by microwave plasma-enhanced chemical vapor deposition,” Journal of Materials Science Vol. 27 (23), 6324–6330 (1992).
[61]. W. Zhu, “Vacuum Microelectronics,” John Wiley & Sons (2001).
[62]. C. A. Spindt, I. Brodie, L. Humphrey, and E. R. Westerberg, “Physical properties of thin field emission cathode with molybdenum cones,” J. Appl. Phys. Vol. 47, 5248–5263 (1976).
[63]. W. B. Choi, J. J. Cuomo, V. V. Zhirnov, A. F. Myers, and J. J. Hren, “ Field emission from silicon and molybdenum tips coated with diamond powder by dielectrophoresis,” Appl. Phys. Lett. Vol. 68(5), 720–722 (1995).
[64]. 羅聖全, “以先進影像能譜電鏡技術:研究銅金屬化製程中低介電常數材料之介電性質與熱穩定性,” Ch.2, 國立清華大學工程與系統科學系博士論文 (2003).
[65]. R. H. Fowler and L. Nordheim, “Electron emission in intense electric fields,” Proc. R. Soc. Lond. (A) Vol. 119, 173–178 (1928).
[66]. P. D. Serapinas, Y. S. Shalkauskas, and Zh. Prikl. Spektrosk, “Homology and concentration sensitivity in equilibrium excitation,” 251496–251501(Translation) (1976).
[67]. N. K. Podder, J. A. Johnson III, C. T. Raynor, S. D. Loch, C. P. Balance, and Pindzola M. S, “Helium line intensity ratio in microwave-generated plasmas,” Phys. Plasmas Vol. 11, 115437–115443 (2004).
[68]. Stephen J. Harris, “Mechanism for diamond growth from methyl radicals,” Appl. Phys. Lett. Vol. 56, 2298–2300 (1990).
[69]. Chuan-Sheng Wang, Huang-Chin Chen, Hsiu-Fung Cheng, and I-Nan, Lin, “Growth behavior of nanocrystalline diamond films on ultranano crystalline diamond nuclei: the transmission electron microscopy studies,” J. Appl. Phys. Vol. 105, 1243111–1243117 (2009).
[70]. O. A. Williams, M. Daenen, J. D'Haen, K. Haenen, J. Maes, V. V. Moshchalkov, M. Nesládek, and D. M. Gruen, “Comparison of the growth and properties of ultrananocrystalline diamond and nanocrystalline diamond,” Diamond Relat. Mater. Vol. 15, 654–658 (2006).
[71]. S. Jiao, A. Sumant, M. A. Kirk, D. M. Gruen, A. R. Krauss, and O. Auciello, “Microstructure of ultrananocrystalline diamond films grown by microwave Ar–CH4 plasma chemical vapor deposition with or without added H2,” J. Appl. Phys. Vol. 90, 118–122 (2001).
[72]. S. J. Askari, F. Akhtar, G. C. Chen, Q. He, F. Y. Wang, X. M. Meng, and F. X. Lu, “Synthesis and characterization of nano-crystalline CVD diamond film on pure titanium using Ar/CH4/H2 gas mixture,” Materials Letters Vol. 61, 2139–2142 (2007).
[73]. A. C. Ferrari and J. Robertson, “Interpretation of Raman spectra of disordered and amorphous carbon,” Phys. Rev. (B) Vol. 63, 1214051–1214054 (2000).
[74]. James Birrell, J. E. Gerbi, O. Auciello, J. M. Gibson, D. M. Gruen, and J. A. Carlisle, “ Bonding structure in nitrogen doped ultrananocrystalline diamond,” J. Appl. Phys. Vol. 93, 5606–5612 (2003).
[75]. H. Kuzmany, R. Pfeiffer, and N. Salk, “ The mystery of the 1140 cm-1 Raman line in nanocrystalline diamond films,” Carbon Vol. 42, 911–917 (2004).
[76]. J. Ma, N. Michael, R. Ashfold, and Y. A. Mankelevich, “Validating optical emission spectroscopy as a diagnostic of microwave activated CH4/Ar/H2 plasmas used for diamond chemical vapor deposition,” J. Appl. Phys. Vol. 105, 0433021–04330212 (2009).
[77]. G. Balestrino, M. Marinelli, E. Milani, A. Paoletti, I. Pinter, A. Tebano, and P. Paroli, “Growth of diamond films: General correlation between film morphology and plasma emission spectra,” Appl. Phys. Lett. Vol. 62, 879–881 (1993).
[78]. Z. Shpilman, Sh. Michaelson, R. Kalish, and A. Hoffman, “Field emission measurements from carbon films of a predominant nano-crystalline diamond character grown by energetic species,” Diamond Relat. Mater. Vol. 15, 846–849 (2006).
[79]. P. T. Joseph, N. H. Tai, H. Niu, U. A. Palnitkar, W. F. Pong, H. F. Cheng, and I. N. Lin, “Structural modification and enhanced field emission on ultrananocrystalline diamond films by nitrogen ion implantation,” Diamond Relat. Mater. Vol. 17, 1812–1816 (2008).
[80]. S. G. Wang, Q. Zhan, S. F. Yoon, J. Ahn, Q. Wang, Q. Zhou, and D. J. Yang, “Electron field emission properties of nano-, submicro- and micro-diamond films,” Phys. Stat. Sol. (a), Vol. 193, 546–551 (2002).
[81]. P. W. May, J. N. Harvey, J. A. Smith, and Yu. A. Mankelevich, “Reevaluation of the mechanism for ultrananocrystalline diamond deposition from Ar/CH4/H2 gas mixtures,” J. Appl. Phys. Vol. 99, 1049071–1049078 (2006).
[82]. Chao Liu, Xingcheng Xiao, Jian Wang, Bing Shi, Vivekananda P. Adiga, Robert W. Carpick, John A. Carlisle, and Orlando Auciello, “Dielectric properties of hydrogen-incorporated chemical vapor deposited diamond thin films,” J. Appl. Phys. Vol. 102, 0741151–0741157 (2007).
[83]. V. Mortet, O. Elmazria, M. Nesladek, M. B. Assouar, G. Vanhoyland, J. D'Haen, M. D. Olieslaeger, and P. Alnot, “Surface acoustic wave propagation in aluminum nitride-unpolished freestanding diamond structures,” Appl. Phys. Lett. Vol. 81, 1720–1722 (2002).
[84]. M. Aggleton, J. C. Burton, and P. Taborek, “Cryogenic vacuum tribology of diamond and diamond-like carbon films,” J. Appl. Phys. Vol. 106, 0135041–0135046 (2009).
[85]. Y. C. Lee, S. J. Lin, D. Pradhan, and I. N. Lin, “Improvement on the growth of ultrananocrystalline diamond by using pre-nucleation technique,” Diamond Relat. Mater. Vol. 15, 353–356 (2006).