ORIENTED TIN-DOPED INDIUM OXIDE-FILMS ON [001] PREFERRED ORIENTED POLYCRYSTALLINE ZNO FILMS

[111]-oriented tin-doped indium oxide (ITO) films were deposited by rf magnetron sputtering on ZnO-coated glass substrates (ZnO/glass). The ZnO underlayers were also deposited by rf magnetron sputtering and have been known to exhibit [001] preferred orientation in a wide range of deposition conditions. The X-ray diffraction profiles of the ITO films deposited on the ZnO/glass showed predominant [111] orientation without any differently oriented crystallites, whereas the ITO films deposited on bare glass substrates (ITO/glass) under the same deposition conditions showed [100]-preferred orientation with small areas of several other orientations. A mechanism of the heteroepitaxial growth of In2O3(111)parallel to ZnO(001) was explained by comparing the atomic configurations of oxygen between the oxygen mostly dense-packed planes of In2O3 and ZnO parallel to In2O3(111) and ZnO(001) planes, respectively. Sn concentrations and lattice constants of the [111]-oriented films (ITO/ZnO/glass) were found to be greater than those of [100] preferred oriented films (ITO/glass) in spite of the fact that the target and deposition conditions were the same, which could be associated with the electrical properties of the films.