Atomic layer chemical vapor deposition of TiO2 - Low temperature epitaxy of rutile and anatase

This study demonstrates that atomic layer chemical vapor deposition is an excellent technique for growing epitaxial TiO2 thin films at low temperatures. Using TiI4 and H2O2 as precursors, both the rutile and anatase phases could be deposited. Anatase is invariably obtained at lower deposition temperatures, but the temperature of the anatase/rutile phase boundary is affected by the substrate material chosen. Phase-pure rutile was obtained down to 275 degrees C on a-Al2O3 (012), while phase-pure anatase was obtained up to 375 degrees C on MgO (001). The rutile phase was found to grow epitaxially on both alpha-A1203 (012) and alpha-Al2O3 (001) substrates with the in-plane orientational relationships [010](rutile)//[100](alpha-Al2O3); [101](rutile)//[121](alpha-Al2O3) and [001](rutile)//[120](alpha-Al2O3), and [010](rutile)//[100](alpha-Al2O3,) respectively. The anatase phase was found to grow epitaxially on MgO (0 0 I) with the in-plane orientational relationships [010](anatase)//[010](MgO) and [001](anatase)//[100](MgO). The rho scan X-ray diffraction measurements verified that epitaxy was still obtained at a deposition temperature of 375 degrees C. This deposition temperature is considerable lower than those commonly applied to realize heteroepitaxy of titanium oxide films. (C) 2000 The Electrochemical Society. S0013-4651(00)01-073-9. All rights reserved.