Erbium-doped TiO2 (TiO2:Er) thin films with the anatase structure have been prepared on Si substrate by laser ablation. Sharp and intense Er-related emission in the visible region as well as in the IR region has been observed under over-band-gap excitation. The broad photoluminescence (PL) peaking at about 530 nm newly appears at low temperature. It has been understood that the broad PL is induced by an optically assisted reduction effect that is caused by both the H2O adsorption and the reduction process of TiO2 to Ti2O3 by UV illumination. In the IR region, Er-related emission consisted of one main peak located at 1.534 μm and many subpeaks located at around 1.54 μm can be observed even at room temperature. The drastic thermal quenching of the Er-related 1.54 μm emission is also considered due to the optically assisted reduction effect.

A large-area electron cyclotron resonance (ECR) plasma is generated by using permanent magnets and applying the whistler-mode launching of microwaves. A uniform plasma is produced with the uniformity of ±3.5% over 20 cm and ±1.8% over 16 cm in diameter; the plasma space potential is about 17 V with the uniformity of ±1% over 20 cm. The maximum ion current density is about 11.5 mA·cm-2. The purity of the produced plasma is high. No damage was found after the operation for 100 h with the microwave power of 600 W.

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Ti–O films were deposited under various conditions by RF reactive ion plating. The structures of the TiO2 films were controlled using various parameters such as substrate temperature, RF power, deposition rate, and pressure of reactive gas. By changing the deposition rate at the substrate temperature of 250°C, the crystal structure could be changed from an anatase phase to a rutile phase. In other words, a rutile structure could be deposited even at a low substrate temperature. The emission spectra of ions and excited species in the plasma were measured by optical emission spectroscopy (OES). Relative spectral intensities of these species were studied. The resulting relative relationship of emission intensities of Ti* and O2 + was found to influence reactions in Ti–O film formation.