Conductivity in transparent anatase TiO 2 films epitaxially grown by reactive sputtering deposition

Abstract

The synthesis of semiconducting TiO 2 thin films deposited by reactive sputtering is discussed. In particular, defect doping of the anatase polymorph that is epitaxial stabilized on (0 0 1) LaAlO 3 was explored using either oxygen or water vapor as the oxidizing species. For films grown in oxygen, a transition from insulating to metallic conductivity of the films is observed as the O 2 pressure is reduced. X-ray diffraction measurements show the presence of the Ti n O 2 n−1 phase when the oxygen pressure is reduced sufficiently to induce conductive behavior. Hall measurements indicate that these materials are p-type. In contrast, the use of water vapor as the oxidizing species enabled the formation of n-type semiconducting TiO 2 with carrier density on the order of 10 18 cm −3 and mobility of 10–15 cm 2/V s.