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 e xcellent technique for growing epitaxial TiO2 thin films at low temperature s. Using TiI4 and H2O2 as precursors, both the rutile and anatase phases co uld be deposited. Anatase is invariably obtained at lower deposition temper atures, but the temperature of the anatase/rutile phase boundary is affecte d 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-pla ne orientational relationships [010](rutile)//[100](alpha-Al2O3); [101](rut ile)//[121](alpha-Al2O3) and [001](rutile)//[120](alpha-Al2O3), and [010](r utile)//[100](alpha-Al2O3,) respectively. The anatase phase was found to gr ow 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 con siderable lower than those commonly applied to realize heteroepitaxy of tit anium oxide films. (C) 2000 The Electrochemical Society. S0013-4651(00)01-0 73-9. All rights reserved.