Toshihisa Kamiyama

High rate deposition of TiO2 by DC sputtering of the TiO2-X target

Abstract A new sputter method for high rate deposition of TiO 2 was developed for application to the common planar magnetron sputter system. In this method, DC power is applied to plasma sprayed TiO 2− X targets using a sputter gas of a few percent of O 2 diluted with Ar and then TiO 2 films are deposited with a high deposition rate (eight times higher than that by the conventional method) and a good uniformity of thickness and refractive-index distribution.

Electrical and optical properties of Nb-doped TiO2 films deposited by dc magnetron sputtering using slightly reduced Nb-doped TiO2−x ceramic targets

Nb-doped anatase TiO2 films were deposited on unheated glass by dc magnetron sputtering using slightly reduced Nb-doped TiO2−x targets (Nb concentration: 3.7 and 9.5 at. %) with various hydrogen or oxygen flow ratios. After postannealing in a vacuum (6×10−4 Pa) at 500 °C for 1 h, both films were crystallized into the polycrystalline anatase TiO2 structure. The resistivity decreased from 1.6×10−3 to 6.3×10−4 Ω cm with increasing Nb concentration from 2.8 to 8.0 at. %, where the carrier density increased from 5.4×1020 to 2.0×1021 cm−3 and the Hall mobility was almost constant at 5–7 cm2 V−1 s−1. The films exhibited a high transparency of over 60%–80% in the visible region.

High rate deposition of photocatalytic TiO2 films by dc magnetron sputtering using a TiO2−x target

Photocatalytic TiO2 films were deposited on glass substrates by dc magnetron sputtering using a slightly reduced TiO2−x target (2−x=1.986; conductivity, 3.7 S cm−1; density, 4.21 g/cm3). The variation in the deposition rate as a function of the O2 flow ratio did not show a hysteresis curve at the “transition region” as seen in the case of a Ti metal target. The deposition rate using the TiO2−x target in 100% Ar gas was approximately seven times higher than that using the Ti metal target in an “oxide mode.” The films postannealed in air at temperatures ≥200 °C showed excellent photodecomposition characteristics of acetaldehyde (CH3CHO) as well as photoinduced hydrophilicity.

Nb-doped TiO 2 films for transparent conductive electrodes with low resistivity deposited by dc magnetron sputtering using a TiO 2-x –Nb 2 O 5-x target

Nb-doped anatase TiO 2 films were deposited on unheated glass by dc magnetron sputtering using a slightly reduced TiO 2-x –Nb 2 O 5-x target with oxygen flow ratios [O 2 /(Ar+O 2 )] in the range from 0.00 to 0.20%. After post-annealing in a vacuum (6 × 10 −4 Pa) at 500 and 600 °C for 1 h, the films were crystallized into the polycrystalline anatase TiO 2 structure. The resistivity of the both films decreased to 6.3-6.8 × 10 −4 Ω·cm with increasing [O 2 /(Ar+O 2 )] to 0.10%, where the carrier density and Hall mobility were 1.9-2.0 × 10 21 cm −3 and 4.9-5.0 cm 2 ·V −1 ·s −1 , respectively. The films exhibited high transparency of over 60-70% in the visible region of light.