A-plane sapphire: A well-matched substrate for epitaxial growth of indium. tin oxide

Indium tin oxide (ITO) thin films were grown on the (11 (2) over bar0) surface of sapphire using fast-pulse laser deposition. It was found that when the oxygen pressure was above 2.66 Pa, the growth was epitaxial with the [111] direction perpendicular to the substrate. The epitaxial relation and crystal quality were evaluated by using high-resolution X-ray diffraction, which showed distinct pendellosung oscillations in theta-2 theta scan of the ITO(222) reflection. The in-plane orientation relationship, ITO [3 (3) over bar0]//Al2O3 [(5) over bar 501] and ITO [(1) over bar /4,(3) over bar /4,1]//Al2O3 [0001], was identified by X-ray phi scan, where no other domains with different orientations could be detected. Good values of mobility, >30 cm(2)/Vs, and resistivity, similar to 2 x 10(-4) ohm cm, were measured by the Hall and van der Pauw methods at room temperature. (C) 2007 Elsevier B.V. All rights reserved.