Material characteristics of sputter-deposited Zr-doped In2O3/ZnO heterostructures on sapphire (0001) substrates

5 wt.% Zr-doped In2O3 (Zr-In2O3) films with thicknesses from 95 to 220 nm were grown on 90 nm-thick ZnO-buffered sapphire (0001) substrates by radio-frequency magnetron sputtering in an oxygen-deficient atmosphere. The dependence on thickness of the structural information and electrical properties of the Zr-In2O3 films on the ZnO-fuffered sapphire substrates was studied. The X-ray diffraction patterns show that the (002)-textured ZnO buffer-layer is a good template for the growth of the highly (222)-textured In2O3 films on the sapphire substrate. The surface of the Zr-In2O3 film becomes rougher as the film thickness increases, perhaps because of the formation of larger mounds on the film surface as the thickness of Zr-In2O3 increases. The carrier concentration increased markedly from 5.8 × 1020 to 1.83 × 1021 cm− 3 with film thickness from 95 to 220 nm, because more growth-induced defects are formed in the thick Zr-In2O3 film. The large increase in the number of charge carriers and the improvement in the crystalline quality in the film reduce the resistivity of the thicker Zr-In2O3 film.