(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]parallel to Al2O3[020] and ITO[110] parallel to k Al2O3 [001] for the m-plane substrate. For the r-plane substrate, two types of lattice matching were observed: one being ITO[001]parallel to Al2O3[2, 1, -1/2] and ITO[110]parallel to Al2O3 -4/3, -4/3, -2/3], the other being ITO[001]parallel to Al2O3 [1, -1, 1/2] and ITO[110]/Al2O3 [8/3, 4/3, -2/3]. 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 x 10(-4) Omega cm, high carrier concentration of about 2.5 x 10(20)cm(-3), and mobility ranging from 70 to 90cm(2)V(-1) s(-1). (C) 2015 The Japan Society of Applied Physics