Low Resistive TiO2 Deposition by LPCVD Using TTIP and NbF5 in Hydrogen-Ambient
Affiliation(s)
Department of Biomolecular Functional Engineering, Ibaraki University, Hitachi, Japan.
Department of Biomolecular Functional Engineering, Ibaraki University, Hitachi, Japan.
ABSTRACT
Low resistive TiO2 layer was deposited by low pressure chemical vapor deposition (LPCVD) at pressure around 0.25 Pa using titanium-tetra-iso-propoxide (TTIP) and NbF5 in H2-ambient. Acti-vation energy for the deposition rate on the temperature was significantly decreased to 120 kJ/mol as compared with 228 kJ/mol for the deposition in H2 without NbF5. The deposition rate linearly increased with NbF5 supply rate but gradually decreased with H2 supply rate indicated that F on the deposition surface acts as catalyst for TTIP-dissociation but is non-activated by hydrogen. Resistivity of the layer was decreased by NbF5 supply depending on the deposition temperature with the activation energy of 319 kJ/mol, whereas the energy was 244 kJ/mol for the layer deposited in H2 without NbF5. The dependence of resistivity on NbF5. and H2 supply rates suggested that the doping should be performed by sufficient NbF5 and H2 supply rate to improve the crystallinity. As a result of the optimization, the resistivity was successfully reduced to 5 × 10-2 Ω·cm. Optical transmission spectra in UV-Vis region indicated that significant absorption observed for the layer deposited in H2 was notably decreased by using NbF5. The improved optical property was better than that for the layer deposited in O2-ambient.
Low resistive TiO2 layer was deposited by low pressure chemical vapor deposition (LPCVD) at pressure around 0.25 Pa using titanium-tetra-iso-propoxide (TTIP) and NbF5 in H2-ambient. Acti-vation energy for the deposition rate on the temperature was significantly decreased to 120 kJ/mol as compared with 228 kJ/mol for the deposition in H2 without NbF5. The deposition rate linearly increased with NbF5 supply rate but gradually decreased with H2 supply rate indicated that F on the deposition surface acts as catalyst for TTIP-dissociation but is non-activated by hydrogen. Resistivity of the layer was decreased by NbF5 supply depending on the deposition temperature with the activation energy of 319 kJ/mol, whereas the energy was 244 kJ/mol for the layer deposited in H2 without NbF5. The dependence of resistivity on NbF5. and H2 supply rates suggested that the doping should be performed by sufficient NbF5 and H2 supply rate to improve the crystallinity. As a result of the optimization, the resistivity was successfully reduced to 5 × 10-2 Ω·cm. Optical transmission spectra in UV-Vis region indicated that significant absorption observed for the layer deposited in H2 was notably decreased by using NbF5. The improved optical property was better than that for the layer deposited in O2-ambient.
Cite this paper
Yamauchi, S. , Ishibashi, K. and Hatakeyama, S. (2015) Low Resistive TiO2 Deposition by LPCVD Using TTIP and NbF5 in Hydrogen-Ambient. Journal of Crystallization Process and Technology, 5, 15-23. doi: 10.4236/jcpt.2015.51003.
Yamauchi, S. , Ishibashi, K. and Hatakeyama, S. (2015) Low Resistive TiO2 Deposition by LPCVD Using TTIP and NbF5 in Hydrogen-Ambient. Journal of Crystallization Process and Technology, 5, 15-23. doi: 10.4236/jcpt.2015.51003.
References
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http://dx.doi.org/10.1016/S1010-6030(03)00205-3 [3] Martinet, C., Paillard, V., Gagnaire, A. and Joseph, J. (1997) Deposition of SiO2 and TiO2 Thin Films by Plasma Enhanced Chemical Vapor Deposition for Antireflection Coating. Journal of Non-Crystalline Solids, 216, 77-82.
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http://dx.doi.org/10.1063/1.2434005 [8] Hoang, N.L., Yamada, N., Hitosugi, T., Kasai, J., Nakao, S., Shimada, T. and Hasegawa, T. (2008) Low-Temperature Fabrication of Transparent Conducting Anatase Nb-Doped TiO2 Films by Sputtering. Applied Physics Express, 1, 115001-115003.
http://dx.doi.org/10.1143/APEX.1.115001 [9] Zhang, A. and Griffin, L. (1995) Gas-Phase Kinetics for TiO2: Hot-Wall Reactor Results. Thin Solid Films, 263, 65-71.
http://dx.doi.org/10.1016/0040-6090(95)06580-6 [10] Yamauchi, S., Saiki, S., Ishibashi, K., Nakagawa, A. and Hatakeyama, S. (2014) Low Pressure Chemical Vapor Deposition of Nb and F Co-Doped TiO2 Layer. Journal of Crystallization Process and Technology, 4, 79-88.
http://dx.doi.org/10.4236/jcpt.2014.42011 [11] Gao, Y., Perkins, C.L., He, S., Alluri, P., Tran, T., Thevuthasan, S. and Henderson, M.A. (2000) Mechanistic Study of Metalorganic Chemical Vapor Deposition of (Ba, Sr)TiO3 Thin Films. Journal of Applied Physics, 87, 7430-7437.
http://dx.doi.org/10.1063/1.373005 [12] Yamauchi, S., Ishibashi, K. and Hatakeyama, S. (2014) Low Pressure Chemical Vapor Deposition of TiO2 Layer in Hydrogen-Ambient. Journal of Crystallization Process and Technology, 4, 185-192.
http://dx.doi.org/10.4236/jcpt.2014.44023 [13] Liu, S., Yu, J., Cheng, B. and Jaroniec, M. (2012) Fluorinated Semiconductor Photocatalysts: Tunable Synthesis and Unique Properties. Advances in Colloid and Interface Science, 173, 35-53.
http://dx.doi.org/10.1016/j.cis.2012.02.004 [14] Valentin, C.D., Pacchioni, G. and Selloni, A. (2009) Reduced and n-Type Doped TiO2: Nature of Ti3+ Species. The Journal of Physical Chemistry C, 113, 20543-20552.
http://dx.doi.org/10.1021/jp9061797 [15] Ride, D.R. (2005) CRC Handbook of Chemistry and Physics. CRC Press, LLC, Boca Raton. [16] Urbach, F. (1953) The Long-Wavelength Edge of Photographic Sensitivity and of the Electronic Absorption of Solids. Physical Review, 92, 1324.
http://dx.doi.org/10.1103/PhysRev.92.1324 [17] Tsukada, M., Wakamura, M., Yoshida, N. and Watanabe, T. (2011) Band Gap and Photocatalytic Properties of Ti- Substituted Hydroxyapatite: Comparison with Anatase-TiO2. Journal of Molecular Catalysis A: Chemical, 338, 18-23.
http://dx.doi.org/10.1016/j.molcata.2011.01.017
[1] Wang, R., Hashimoto, K. and Fujishima, A. (1997) Light-Induced Amphiphilic Surfaces. Nature, 388, 431-432.
http://dx.doi.org/10.1038/41233 [2] Mills, A., Lepre, A., Elliott, N., Bhopal, A., Parkin, I.P. and Neill, S.A. (2003) Characterisation of the Photocatalyst Pilkington ActivTM: A Reference Film Photocatalyst? Journal of Photochemistry and Photobiology A: Chemistry, 160, 213-224.
http://dx.doi.org/10.1016/S1010-6030(03)00205-3 [3] Martinet, C., Paillard, V., Gagnaire, A. and Joseph, J. (1997) Deposition of SiO2 and TiO2 Thin Films by Plasma Enhanced Chemical Vapor Deposition for Antireflection Coating. Journal of Non-Crystalline Solids, 216, 77-82.
http://dx.doi.org/10.1016/S0022-3093(97)00175-0 [4] Campbell, S.A., Kim, H.S., Gilmer, D.C., He, B., Ma, T. and Gladfelter, W.L. (1999) Titanium Dioxide (TiO2)-Based Gate Insulators. IBM Journal of Research and Development, 43, 383-392.
http://dx.doi.org/10.1147/rd.433.0383 [5] O’Regan, B. and Grätzel, M. (1991) A Low-Cost, High-Efficiency Solar Cell Based on Dye-Sensitized Colloidal TiO2 Films. Nature, 353, 737-740.
http://dx.doi.org/10.1038/353737a0 [6] Hitosugi, T., Ueda, A., Furubayashi, Y., Hirose, Y., Konuma, S., Shimada, T. and Hasegawa, T. (2006) Fabrication of TiO2-Based Transparent Conducting Oxide Films on Glass by Pulsed Laser Deposition. Japanese Journal of Applied Physics, 46, L86-L88.
http://dx.doi.org/10.1143/JJAP.46.L86 [7] Gillispie, M.A., van Hest, M.F.A.M., Dabney, M.S., Perkins, J.D. and Ginley, D.S. (2007) rf Magnetron Sputter Deposition of Transparent Conducting Nb-Doped TiO2 Films on SrTiO3. Journal of Applied Physics, 101, Article ID: 033125.
http://dx.doi.org/10.1063/1.2434005 [8] Hoang, N.L., Yamada, N., Hitosugi, T., Kasai, J., Nakao, S., Shimada, T. and Hasegawa, T. (2008) Low-Temperature Fabrication of Transparent Conducting Anatase Nb-Doped TiO2 Films by Sputtering. Applied Physics Express, 1, 115001-115003.
http://dx.doi.org/10.1143/APEX.1.115001 [9] Zhang, A. and Griffin, L. (1995) Gas-Phase Kinetics for TiO2: Hot-Wall Reactor Results. Thin Solid Films, 263, 65-71.
http://dx.doi.org/10.1016/0040-6090(95)06580-6 [10] Yamauchi, S., Saiki, S., Ishibashi, K., Nakagawa, A. and Hatakeyama, S. (2014) Low Pressure Chemical Vapor Deposition of Nb and F Co-Doped TiO2 Layer. Journal of Crystallization Process and Technology, 4, 79-88.
http://dx.doi.org/10.4236/jcpt.2014.42011 [11] Gao, Y., Perkins, C.L., He, S., Alluri, P., Tran, T., Thevuthasan, S. and Henderson, M.A. (2000) Mechanistic Study of Metalorganic Chemical Vapor Deposition of (Ba, Sr)TiO3 Thin Films. Journal of Applied Physics, 87, 7430-7437.
http://dx.doi.org/10.1063/1.373005 [12] Yamauchi, S., Ishibashi, K. and Hatakeyama, S. (2014) Low Pressure Chemical Vapor Deposition of TiO2 Layer in Hydrogen-Ambient. Journal of Crystallization Process and Technology, 4, 185-192.
http://dx.doi.org/10.4236/jcpt.2014.44023 [13] Liu, S., Yu, J., Cheng, B. and Jaroniec, M. (2012) Fluorinated Semiconductor Photocatalysts: Tunable Synthesis and Unique Properties. Advances in Colloid and Interface Science, 173, 35-53.
http://dx.doi.org/10.1016/j.cis.2012.02.004 [14] Valentin, C.D., Pacchioni, G. and Selloni, A. (2009) Reduced and n-Type Doped TiO2: Nature of Ti3+ Species. The Journal of Physical Chemistry C, 113, 20543-20552.
http://dx.doi.org/10.1021/jp9061797 [15] Ride, D.R. (2005) CRC Handbook of Chemistry and Physics. CRC Press, LLC, Boca Raton. [16] Urbach, F. (1953) The Long-Wavelength Edge of Photographic Sensitivity and of the Electronic Absorption of Solids. Physical Review, 92, 1324.
http://dx.doi.org/10.1103/PhysRev.92.1324 [17] Tsukada, M., Wakamura, M., Yoshida, N. and Watanabe, T. (2011) Band Gap and Photocatalytic Properties of Ti- Substituted Hydroxyapatite: Comparison with Anatase-TiO2. Journal of Molecular Catalysis A: Chemical, 338, 18-23.
http://dx.doi.org/10.1016/j.molcata.2011.01.017