Molecular Layer Deposition of Titanicone Films using TiCl4 and Ethylene Glycol or Glycerol: Growth and Properties

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• 作者：Aziz I. Abdulagatov ; Robert A. Hall ; Jackson L. Sutherland ; Byoung H. Lee ; Andrew S. Cavanagh ; Steven M. George
• 刊名：Chemistry of Materials
• 出版年：2012
• 出版时间：August 14, 2012
• 年：2012
• 卷：24
• 期：15
• 页码：2854-2863
• 全文大小：558K
• 年卷期：v.24,no.15(August 14, 2012)
• ISSN：1520-5002

文摘

Molecular layer deposition (MLD) techniques were used to grow titanium-containing hybrid organic鈥搃norganic films known as 鈥渢itanicones鈥?using titanium tetrachloride (TiCl₄) and either ethylene glycol (EG) or glycerol (GL). The surface chemistry for titanicone MLD was self-limiting versus TiCl₄ and either EG or GL exposures. Quartz crystal microbalance (QCM) measurements observed a film growth rate of 83 ng/cm²/cycle using TiCl₄ and EG from 90 to 115 掳C. The growth rate then decreased significantly at 135 掳C. X-ray reflectivity (XRR) studies yielded a growth rate of 4.5 脜/cycle with a constant density of 1.8 g/cm³ from 90 to 115 掳C. The growth rate measured using XRR also decreased to 1.5 脜/cycle at 135 掳C. Titanicone films were grown using TiCl₄ and GL at higher temperatures between 130 and 210 掳C. GL should increase the bridging between the polymer chains in the titanicone film and change film properties and improve film stability. The film growth rates decreased with temperature from 49 ng/cm²/cycle at 130 掳C to 34 ng/cm²/cycle at 210 掳C. XRR studies were consistent with a temperature-dependent film growth and measured growth rates of 2.8 脜/cycle at 130 掳C and 2.1 脜/cycle at 210 掳C. Nanoindentation experiments revealed that the elastic modulus and hardness of the titanicone films grown using GL were much higher than titanicone films grown using EG. Annealing the titanicone films to 600 掳C in air removed the carbon constituents and yielded TiO₂ films with a density of 3.3 g/cm³ that is slightly higher than the density of TiO₂ ALD films grown at 115 掳C. The titanicone films absorbed light in the ultraviolet, and the absorption threshold was consistent with an optical bandgap of 3.6 eV. Prolonged ultraviolet exposures on the titanicone films produced TiO₂ films with a low density of 2.7 g/cm³.

Keywords:

layer+deposition&qsSearchArea=searchText">molecular layer deposition; thin films; hybrid organic-inorganic; titanium oxide; layer+deposition&qsSearchArea=searchText">atomic layer deposition