TiN和Si衬底上原子层沉积CeO 2薄膜的结构、化学和光学性质
Structural, Chemical and Optical Properties of Cerium Dioxide Film Prepared by Atomic Layer Deposition on TiN and Si Substrates
摘要：
通过原子层沉积（ALD）在250 °C下在Si和TiN衬底上沉积二氧化铈（CeO 2）的薄膜。ALD生长在两个衬底上产生具有多晶立方相的CeO 2膜。然而，薄膜显示出沿<200>结晶方向的CeO 2/Si或<111>CeO 2/TiN的择优取向，如通过X射线衍射所揭示的。此外，CeO 2膜的界面粗糙度取决于衬底而不同。X射线光电子能谱学（XPS）分析表明，CeO 2/Si中Ce 3+的相对浓度为22.0%，CeO 2/TiN中Ce 3+的相对浓度约为18%.这样的值指示约10%的偏离化学计量并且指示膜中存在氧空位。尽管如此，CeO 2带隙能量和在550 nm处的折射率对于CeO 2/Si分别为3.54+/-0.63 eV和2.3，对于CeO 2/TiN分别为3.63+/-0.18 eV和2.4。我们的研究结果扩展了ALD沉积的CeO 2的结构和化学性质的知识，无论是在Si或TiN衬底上，底层膜的差异和相似性，从而有助于提高使用CeO 2通过ALD沉积预见在广泛的应用。
英文摘要：
Thin films of cerium dioxide (CeO2) were deposited by atomic layer deposition (ALD) at 250 °C on both Si and TiN substrates. The ALD growth produces CeO2 films with polycrystalline cubic phase on both substrates. However, the films show a preferential orientation along <200> crystallographic direction for CeO2/Si or <111> for CeO2/TiN, as revealed by X-ray diffraction. Additionally, CeO2 films differ in interface roughness depending on the substrate. Furthermore, the relative concentration of Ce3+ is 22.0% in CeO2/Si and around 18% in CeO2/TiN, as obtained by X-ray photoelectron spectroscopy (XPS). Such values indicate a ~10% off-stoichiometry and are indicative of the presence of oxygen vacancies in the films. Nonetheless, CeO2 bandgap energy and refractive index at 550 nm are 3.54+/-0.63 eV and 2.3 for CeO2/Si, and 3.63+/-0.18 eV and 2.4 for CeO2/TiN, respectively. Our results extend the knowledge on the structural and chemical properties of ALD-deposited CeO2 either on Si or TiN substrates, underlying films differences and similarities, thus contributing to boost the use of CeO2 through ALD deposition as foreseen in a wide number of applications.
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