(110)-oriented indium tin oxide films grown on m- and r-plane sapphire substrates

Indium tin oxide (ITO) thin films have been deposited by pulsed laser deposition on m-plane (100) and r-plane (012) sapphire substrates. For both substrates, the films were grown with their [110] direction perpendicular to the substrate planes under the conditions of high growth temperature and high oxygen pressure. Their in-plane epitaxial relations with the substrates were identified to be ITO[001] ∥ Al2O3[020] and for the m-plane substrate. For the r-plane substrate, two types of lattice matching were observed: one being and , the other being and . The electrical properties were measured by the Hall effect and van der Pauw methods at room temperature. All of the samples have low electrical resistivity on the order of 3.0 × 10−4 Ω cm, high carrier concentration of about 2.5 × 1020 cm−3, and mobility ranging from 70 to 90 cm2 V−1 s−1.