TiO₂ thin films of various thicknesses have been deposited on silicon at low-temperature by PECVD operating in continuous mode (T < 130 C) and pulsed mode (T < 80 C) using oxygen/titanium isopropoxide low-pressure inductively coupled plasma. The study of the crystallinity and microstructure of the films by atomic force microscopy, scanning electron microscopy and x-ray diffraction allowed showing that the roughness and amount of anatase are closely related to the film thickness. The coalescence of large polycrystalline columns emerging from an assembly of thin columns was found to happen at a critical thickness, at about 150 nm in the continuous mode and 250 nm in the pulsed mode. Real time in situ spectroscopic ellipsometry study allowed to monitor the growth and to determine this critical thickness for both plasma modes. The change of morphology type to large columnar structure is associated with an important increase in the photocatalytic activity. The determination of this coalescence thickness by ellipsometry may provide an interesting method to evaluate the impact of process parameters on TiO₂ thin films characteristics.

使用氧/异丙醇钛低压电感耦合等离子体，通过PECVD在连续模式（T < 130 C）和脉冲模式（T < 80 C）下操作，在低温下在硅上沉积了各种厚度的TiO ₂薄膜。通过原子力显微镜、扫描电子显微镜和 X 射线衍射对薄膜的结晶度和微观结构的研究表明，锐钛矿的粗糙度和含量与薄膜厚度密切相关。发现从一组薄柱中出现的大多晶柱的聚结发生在临界厚度处，连续模式下约为 150 nm，脉冲模式下约为 250 nm。现场实时椭圆偏振光谱研究允许监测生长并确定两种等离子体模式的临界厚度。形态类型向大柱状结构的变化与光催化活性的重要增加有关。通过椭圆光度法确定这种聚结厚度可以提供一种有趣的方法来评估工艺参数对 TiO ₂薄膜特性的影响。