Low Resistive TiO2 Deposition by LPCVD Using TTIP and NbF5 in Hydrogen-Ambient

Satoshi  Yamauchi; Kazuhiro  Ishibashi; Sakura  Hatakeyama

doi:10.4236/jcpt.2015.51003

Satoshi Yamauchi, Kazuhiro Ishibashi, Sakura Hatakeyama^*

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.

Keywords: LPCVD-TiO₂, H₂-Ambient, Nb and F Doping, Low-Resistive TiO₂, Optical Transmittance

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.

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