The electronic structure of In2O3 has been studied for the first time using a first-principles calculation method based on the density functional theory. Although the complexity of the crystal structure of In2O3 which contained 40 atoms in its unit cell had prevented studies of its electronic structure, we were able to study it using the characteristic of minimum basis sets of the linear muffin-tin orbital method with atomic sphere approximation. The calculated partial density of states (PDOS) showed that the valence bands were composed mainly of oxygen 2p-like states and the conduction bands consisted mainly of indium 5s-like states with free-electron-like character. The results of PDOS analysis were used to analyze the spectra from X-ray photoelectron spectroscopy and bremsstrahlung isochromat spectroscopy. Calculated results were also used to interpret optoelectronic properties of tin-doped indium oxide.

Oriented thin-film tin-doped indium oxide (ITO) was heteroepitaxially grown on optically polished (100) or (111) planes of single-crystalline yttria-stabilized zirconia (YSZ) substrates using e-beam evaporation or dc magnetron sputtering techniques. Pole figure x-ray diffraction analyses revealed that the heteroepitaxial relations were (001)ITO∥(001)YSZ, [100]ITO∥[100]YSZ, and (111)ITO∥(111)YSZ, [110]ITO∥[110]YSZ, respectively. X-ray rocking curve analyses and Rutherford backscattering spectrometry revealed that the e-beam evaporated heteroepitaxial ITO films had much higher crystallinity than the one deposited by dc magnetron sputtering. Both carrier density and Hall mobility of the e-beam evaporated heteroepitaxial films showed steady increases in a wide temperature range, which could be interpreted in terms of the increasing Sn-doping efficiency caused by the improvement of the crystallinity of In2O3 host lattice, and hence the decreasing Sn-based neutral scattering centers.

Highly oriented thin film In2O3 was heteroepitaxially grown on an optically polished (001) plane of single crystalline yttria stabilized zirconia (YSZ) substrate using molecular beam epitaxy (MBE). The full-width at half maximum (FWHM) of the X-ray rocking curve was 0.08° for 200-nm-thick In2O3 layers indicating excellent uniformity of the crystallographic orientation compared with the heteroepitaxially-grown In2O3 deposited by a conventional method such as electron-beam (e-beam) evaporation. The minimum yield (χmin ) of the MBE grown In2O3 film obtained from Rutherford backscattering (RBS) spectra was also extremely small with a value of 3.1% implying high crystallinity with very low lattice defect density.

Heteroepitaxial growth of tin-doped indium oxide (ITO) and non-doped indium oxide (IO) thin films was carried out on single-crystal yttria-stabilized zirconia substrates by molecular beam epitaxy. The surface morphology of these epitaxial films was characterized by scanning electron microscopy. The doped ITO and non doped IO epitaxial films showed drastic changes in surface morphology, which suggested that Sn acted not only as a dopant but also as a growth modifier for IO films. The surface morphology analysis of IO and ITO films revealed a growth rate enhancement by Sn doping along the <111> direction.

Growth condition dependence of morphology and electric properties of ZnO films on sapphire substrates prepared by molecular beam epitaxy Molar fraction and substrate orientation effects on carbon doping in InGaAs grown by solid source molecular beam epitaxy using carbon tetrabromide Heteroepitaxial growth of nondoped indium oxide ͑IO͒ and Sn-doped indium oxide ͑ITO͒ thin films was carried out on optically polished single-crystalline yttria-stabilized zirconia ͑YSZ͒ substrates by molecular-beam epitaxy. The surface morphology of the epitaxial films was analyzed by field-emission-type scanning electron microscopy. The IO and ITO films showed quite different surface morphology, implying that the crystal-growth mechanisms were strongly affected by the Sn doping. The surface migration of In on the ͑111͒ plane should be suppressed with increasing Sn concentration, resulting in the relatively large growth rate along the ͗111͘ direction. The epitaxial IO film deposited on YSZ͑001͒ substrate showed very high mobility (ϭ86 cm 2 /V s) and low carrier density (nϭ3.5ϫ10 18 cm Ϫ3 ). Sn doping by 2.6 at. % increased the carrier density by 6.5 ϫ10 20 cm Ϫ3 , where doping efficiencies were about 81%.