Epitaxial growth of TiO2 films in a hydroxyl-free atomic layer deposition process

This study demonstrates that TiI4-O-2 is a well working precursor system for epitaxial growth of titanium oxide films in an atomic layer deposition process that is not based on reactions with surface hydroxyl groups. Rutile and anatase were found to grow epitaxially on alpha-Al2O3(0 1 2) and MgO(0 0 1), respectively. The epitaxial relationships were determined by phi-scan and were found to be [0 1 0](rutile)\\ [1 0 0](alpha-Al2O3); [1 0 (1) over bar](rutile)\\[(1) over bar (2) over bar 1](alpha-Al2O3) for the rutile films grown on alpha-Al2O3(0 1 2) and [0 1 0](anatase)\\[0 1 0](MgO) and [0 0 1](anatase)\\[1 0 0](MgO) for the anatase films grown on MgO(0 0 1). These relationships were also confirmed by TEM. For the anatase films grown at higher temperatures, small amounts of rutile were present. The TEM investigation showed that the rutile phase was situated in the grain boundaries between the anatase grains. (C) 2002 Elsevier Science B.V. All rights reserved.