Manipulation of carrier concentration, crystallite size and density in polycrystalline anatase TiO2via amorphous-phase medium range atomic order

Thin-film semiconducting anatase TiO2 finds several applications, including photocatalysis, wherein control over carrier concentration and other material properties would be useful. The present work employs atomic layer deposition to fabricate thin amorphous films of TiO2, which are then annealed into polycrystalline anatase. Variations in the temperature and growth rate for deposition, as well as in the ramp rate and final temperature employed during the annealing, propagate into changes in one or more of the final carrier concentration, crystallite size and bulk density. Many of these surprising findings can be interpreted in terms of medium range atomic order existing in the initial amorphous films, and demonstrate that the order can be manipulated and exploited to some degree.