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Reply by Liu et al.
Applied Surface Science 253 (2007) 4816–4817 www.elsevier.com/locate/apsusc
Discussion
Reply by Liu et al. Lihua Liu a,b, Yuxin Wang c, Kecheng Feng c, Yingai Li a, Weiqing Li a, Chunhong Zhao a, Yongnian Zhao a,* a
National Key Laboratory of Superhard Materials, Jilin University, Changchun, Jilin 130012, China b College of Physics, Jilin Normal University, Jilin, Siping 136000, China c College of Science, Changchun University of Science and Technology, Changchun 130022, China
Abstract The experimental results indicate that the composition of our samples is homogeneous. We have explained the reason why the composition of the BCN film is influenced by the r.f. power. The Fourier transformed infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements suggest that the samples are atomic-level hybrids of B, C and N. # 2006 Elsevier B.V. All rights reserved. Keywords: Homogeneity; Hybrids; Peak
In the earlier experiments, we have tested the homogeneity of the composition of our films by the following method: during the deposition, four small Si substrates were placed on the substrate holder with two under the graphite part of the target and the other two under the h-BN part of the target. After deposition the XPS measurements were done for the four samples. The results indicate that the composition of the four samples is nearly the same. So the composition of our samples is homogeneous. The sputtered ions or ion clusters can obtain more energy and the higher energetic ion bombardment on the substrate are enhanced at higher r.f. power [1,2]. The intense ion bombardment results in a bombardment activated desorption of N, B atoms from the growing surface when the sputtering power is larger than 110 W. Therefore, the atomic fractions of B, N decrease and the fraction of C atoms increases with the increase of sputtering power from 110 W to 130 W. The films are atomic-level hybrids of B, C and N atoms but not a mixture of graphite and h-BN. The FTIR spectra of the samples have four peaks at about 1367 cm 1, 1276 cm 1, 1180 cm 1 and 844 cm 1, which correspond to the in-plane B–N, C–N, B–C and the out-of-plane B–N–B bonds. The results suggest that the films are atomic-level hybrids composed of B, C and N atoms. The absorption peak assigned to B–C bond is sharper than all other identified peaks and asymmetric. This is not an artefact but a real absorption peak. The sharper and asymmetric peak may be due to
DOI of original article: 10.1016/j.apsusc.2006.10.034. * Corresponding author. Tel.: +86 431 8498228. E-mail address: [email protected] (Y. Zhao). 0169-4332/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2006.10.035
that these samples have larger internal stress. The larger internal stress results in the peeling off of the films from the substrates and we have observed the phenomenon. Also the XPS spectra can also provide evidence for atomic-level hybrids. The curve fit of B1s spectrum shows two peaks at 190.0 eV and 191.0 eV. Watanabe et al. and Kunzli et al. report the binding energies of B4C at 188.4 eV and that of BC3.4 at 189.4 eV [3,4]. Yue et al. report B–C peak at 189.5 eV [5]. Lei et al. report BC3.4 at 189.8 eV [6]. Pan et al. report that the peak at 190.0 eV is attributable to electrons originating from boron atoms bonded to carbon [7]. Etou et al. report the B–C peak at 189.6 eV [8]. Therefore, the resolved peak at 190.0 eV can be attributed to B–C bonding. The energy shifts of B1s deconvoluted peaks to a higher binding energy could be explained by the interconnection of boron, carbon and nitrogen due to their different electronegativity [6]. The curve fit of C1s spectrum gives three peaks centered at 284.8 eV, 286.9 eV and 283.7 eV. The binding energies of C1s electrons have been reported to have peaks at 283.0 eVand 284.3 eV for B4C and BC3.4, respectively [3,9]. Tai et al. have reported B–C bond at 283.6 eV [10]. So the resolved peak at 283.7 eV is due to B–C bonding. The above analyses suggest that the samples are atomic-level hybrids of B, C and N. References [1] D.H. Zhang, T.L. Yang, J. Ma, Q.P. Wang, R.W. Gao, H.L. Ma, Appl. Surf. Sci. 158 (2003) 43–48. [2] N.H. Kim, H.W. Kim, Mater. Lett. 58 (2004) 938–943. [3] M.O. Watanabe, T. Sasaki, S. Itoh, K. Mizushima, Thin Solid Films 281– 282 (1996) 334.
L. Liu et al. / Applied Surface Science 253 (2007) 4816–4817 [4] H. Kunzli, P. Gantenbein, R. Steiner, P. Oelhafen, Anal. Chem. 346 (1993) 41. [5] J. Yue, W. Cheng, X. Zhang, D. He, G. Chen, Thin Solid Films 375 (2000) 247–250. [6] M.K. Lei, Q. Li, Z.F. Zhou, I. Bello, C.S. Lee, S.T. Lee, Thin Solid Films 389 (2001) 194.
4817
[7] W.J. Pan, J. Sun, H. Ling, N. Xu, Z.F. Ying, J.D. Wu, Appl. Surf. Sci. 218 (2003) 297–304. [8] Y. Etou, T. Tai, T. Sugiyama, T. Sugino, Diamond Relat. Mater. 11 (2002) 985–988. [9] M.O. Watanabe, S. Itoh, K. Mizushima, Appl. Phys. Lett. 68 (1996) 2962. [10] T. Tai, T. Sugiyama, T. Sugino, Diamond Relat. Mater. 12 (2003) 1117.
Discussion
Reply by Liu et al. Lihua Liu a,b, Yuxin Wang c, Kecheng Feng c, Yingai Li a, Weiqing Li a, Chunhong Zhao a, Yongnian Zhao a,* a
National Key Laboratory of Superhard Materials, Jilin University, Changchun, Jilin 130012, China b College of Physics, Jilin Normal University, Jilin, Siping 136000, China c College of Science, Changchun University of Science and Technology, Changchun 130022, China
Abstract The experimental results indicate that the composition of our samples is homogeneous. We have explained the reason why the composition of the BCN film is influenced by the r.f. power. The Fourier transformed infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements suggest that the samples are atomic-level hybrids of B, C and N. # 2006 Elsevier B.V. All rights reserved. Keywords: Homogeneity; Hybrids; Peak
In the earlier experiments, we have tested the homogeneity of the composition of our films by the following method: during the deposition, four small Si substrates were placed on the substrate holder with two under the graphite part of the target and the other two under the h-BN part of the target. After deposition the XPS measurements were done for the four samples. The results indicate that the composition of the four samples is nearly the same. So the composition of our samples is homogeneous. The sputtered ions or ion clusters can obtain more energy and the higher energetic ion bombardment on the substrate are enhanced at higher r.f. power [1,2]. The intense ion bombardment results in a bombardment activated desorption of N, B atoms from the growing surface when the sputtering power is larger than 110 W. Therefore, the atomic fractions of B, N decrease and the fraction of C atoms increases with the increase of sputtering power from 110 W to 130 W. The films are atomic-level hybrids of B, C and N atoms but not a mixture of graphite and h-BN. The FTIR spectra of the samples have four peaks at about 1367 cm 1, 1276 cm 1, 1180 cm 1 and 844 cm 1, which correspond to the in-plane B–N, C–N, B–C and the out-of-plane B–N–B bonds. The results suggest that the films are atomic-level hybrids composed of B, C and N atoms. The absorption peak assigned to B–C bond is sharper than all other identified peaks and asymmetric. This is not an artefact but a real absorption peak. The sharper and asymmetric peak may be due to
DOI of original article: 10.1016/j.apsusc.2006.10.034. * Corresponding author. Tel.: +86 431 8498228. E-mail address: [email protected] (Y. Zhao). 0169-4332/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.apsusc.2006.10.035
that these samples have larger internal stress. The larger internal stress results in the peeling off of the films from the substrates and we have observed the phenomenon. Also the XPS spectra can also provide evidence for atomic-level hybrids. The curve fit of B1s spectrum shows two peaks at 190.0 eV and 191.0 eV. Watanabe et al. and Kunzli et al. report the binding energies of B4C at 188.4 eV and that of BC3.4 at 189.4 eV [3,4]. Yue et al. report B–C peak at 189.5 eV [5]. Lei et al. report BC3.4 at 189.8 eV [6]. Pan et al. report that the peak at 190.0 eV is attributable to electrons originating from boron atoms bonded to carbon [7]. Etou et al. report the B–C peak at 189.6 eV [8]. Therefore, the resolved peak at 190.0 eV can be attributed to B–C bonding. The energy shifts of B1s deconvoluted peaks to a higher binding energy could be explained by the interconnection of boron, carbon and nitrogen due to their different electronegativity [6]. The curve fit of C1s spectrum gives three peaks centered at 284.8 eV, 286.9 eV and 283.7 eV. The binding energies of C1s electrons have been reported to have peaks at 283.0 eVand 284.3 eV for B4C and BC3.4, respectively [3,9]. Tai et al. have reported B–C bond at 283.6 eV [10]. So the resolved peak at 283.7 eV is due to B–C bonding. The above analyses suggest that the samples are atomic-level hybrids of B, C and N. References [1] D.H. Zhang, T.L. Yang, J. Ma, Q.P. Wang, R.W. Gao, H.L. Ma, Appl. Surf. Sci. 158 (2003) 43–48. [2] N.H. Kim, H.W. Kim, Mater. Lett. 58 (2004) 938–943. [3] M.O. Watanabe, T. Sasaki, S. Itoh, K. Mizushima, Thin Solid Films 281– 282 (1996) 334.
L. Liu et al. / Applied Surface Science 253 (2007) 4816–4817 [4] H. Kunzli, P. Gantenbein, R. Steiner, P. Oelhafen, Anal. Chem. 346 (1993) 41. [5] J. Yue, W. Cheng, X. Zhang, D. He, G. Chen, Thin Solid Films 375 (2000) 247–250. [6] M.K. Lei, Q. Li, Z.F. Zhou, I. Bello, C.S. Lee, S.T. Lee, Thin Solid Films 389 (2001) 194.
4817
[7] W.J. Pan, J. Sun, H. Ling, N. Xu, Z.F. Ying, J.D. Wu, Appl. Surf. Sci. 218 (2003) 297–304. [8] Y. Etou, T. Tai, T. Sugiyama, T. Sugino, Diamond Relat. Mater. 11 (2002) 985–988. [9] M.O. Watanabe, S. Itoh, K. Mizushima, Appl. Phys. Lett. 68 (1996) 2962. [10] T. Tai, T. Sugiyama, T. Sugino, Diamond Relat. Mater. 12 (2003) 1117.