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Abstract: A ZnO thin-film transistor (TFT) with an MgO insulator was fabricated on a silicon (100) substrate using a radiofrequency magnetron sputtering system. The MgO insulator was deposited using the same deposition system; the total pressure during the deposition process was maintained at 5 mTorr, and the oxygen percentage of O2/(Ar + O2) was set at 30%, 50%, or 70%. The process temperature was maintained at below 300 °C. The dielectric constant of the MgO thin layer was approximately 11.35 with an oxygen percentage of 70%. This ZnO TFT displayed enhanced transistor properties, with a field-effect mobility of 0.0235 cm2 V−1 s−1, an I ON/I OFF ratio of ∼105, and an SS value of 1.18 V decade−1; these properties were superior to those measured for the MgO insulators synthesized using oxygen percentages of 30% and 50%. [Copyright &y& Elsevier]

The grain morphology of Si[sub 0.7]Ge[sub 0.3] depends on the number of the primary noncoplanar twin variants formed at the early stage of solid-phase crystallization. The grain with major twin bands of a single twin variant parallel to a {111} plane develops an elongated shape, owing to the preferential growth in a [112] direction along twins. When the grain has major twin bands of two or more noncoplanar twin variants, the growth front between noncoplanar twin bands develops as fast as the [112] direction along twins propagates, because such a growth front is formed from a {111} ledge. As results, the grain becomes more or less equiaxed due to the increasing number of primary, noncoplanar twin variants. © 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We directly observed the crystal structure changes of the Mg x Zn 1 − x O alloy thin film deposited on Si (111) substrates. Through the in situ heating transmission electron microscopy study, it was determined that the crystal structure changes did not occur up to at 400 °C, whereas the disappearance of the hexagonal structure was observed at 500 °C in the layer of nanosized grains. Additionally, the decreased intensity of the Zn L-edge was analyzed in the comparison of the core loss electron energy loss spectroscopy spectra of the Zn L-edge and the Mg K-edge obtained at room temperature and 500 °C. Based on these experimental results, the process of crystal structure changes could be explained by the evaporation of Zn atoms in the Mg x Zn 1 − x O alloy system. This phenomenon is prominent in the improvement of the microstructure of the Mg x Zn 1 − x O alloy thin film by controlling the thermal annealing temperature. [ABSTRACT FROM AUTHOR]

Abstract: The dependence of the MgO sputtering power on the structural and optical properties of epitaxially grown MgZnO thin films on GaN/sapphire substrates by radio-frequency magnetron sputtering was investigated. The photoluminescence investigation showed blue shift of 170 meV in MgZnO film grown at the MgO power of 300 W, compared with the ZnO films grown at the MgO power of 0 W, which was attributed to the enhancement of the Mg incorporation at higher power. In addition, increase in Mg mole fraction with increase in sputtering power of MgO was observed from the PL results, and a maximum of 6.6 at.% Mg was obtained at the MgO power of 300 W. The high-resolution X-ray diffraction and transmission electron microscopy (TEM) investigations revealed that the threading dislocation density in the MgZnO thin films increased with increase in sputtering power. Furthermore, microstructural analysis performed by TEM revealed formation of a thin cubic-like phase in the interface between GaN template and MgZnO thin film, together with increased thickness of the interfacial layer with sputtering power. [Copyright &y& Elsevier]

Abstract: In-doped ZnO films with low mole fraction (0.1, 0.3, 0.6 at.%) were prepared on p-Si (111) at 600 °C by the pulsed laser deposition (PLD). The effect of composition on structures, optical and electrical properties was studied by X-ray diffraction, atomic force microscopy, photoluminescence, and the Hall Effect measurement system. In-doped ZnO film has (101) preferred orientation and UV emissions of ZnO:In films were red shift with increasing In contents and there are no deep-level emissions. The lowest resistivity of 5.6×10−2 Ωcm and highest mobility of 33.1 cm2/Vs was observed at the In content of 0.3 at.%. [Copyright &y& Elsevier]

Abstract: Epitaxial Ba0.5Sr0.5TiO3 (BSTO) thin films were grown on TiN buffered Si (001) substrates by PLD method and the effects of deposition temperature on their crystallinity and microstructure were studied. BSTO thin films were prepared with substrate temperature ranging from 350 to 650°C. The BSTO films grown at below 400°C showed amorphous phase and the film grown at 450°C showed mixed phase of crystalline and amorphous, where crystalline phase was observed only at the top surface portion of the film. The BSTO films with fully crystalline phase were obtained in the samples deposited at above 500°C. The (00 l) preferred orientation and the crystallinity of the BSTO films were improved with increasing the temperature. The dielectric constant, measured at 100kHz and at room temperature, of the BSTO film grown at 650°C was measured to be as high as 1129. [Copyright &y& Elsevier]

Abstract: Epitaxial SrTiO3(STO)/BaTiO3(BTO) artificial superlattices have been grown on TiN buffered Si (001) substrates by pulsed laser deposition method and the effects of stacking periodicity and processing oxygen partial pressure on their crystallinity and dielectric properties were studied. The crystal orientation, epitaxy nature, and microstructure of STO/BTO superlattices were investigated using X-ray diffraction and transmission electron microscopy. The TiN buffer layer and superlattice thin films were grown with cube-on-cube epitaxial orientation relationship of [110](001)films∣∣[110](001)TiN∣∣[110](001)Si. The c-axis lattice parameter of the STO/BTO superlattice decreased from 0.412 nm to 0.406 nm with increasing oxygen partial pressure and the dielectric constants, measured at the frequency of 100 kHz at room temperature, of the superlattices with 2 nm/2 nm periodicity increased from 312 at 1×10−5 Torr to 596 at 1×10−3 Torr. The dielectric constants of superlattices grown at oxygen partial pressure of 1×10−3 Torr increased from 264 to 678 with decreasing periodicity of the superlattices from 10 nm/10 nm to 1 nm/1 nm. [Copyright &y& Elsevier]

Thin films of SrRuO 3 , which is a conductive oxide, have the potential for use as electrode layers in versatile electronic applications, particularly with perovskite structured dielectric and ferroelectric oxide thin films. Moreover, for practical device applications, it is important to develop the deposition process of low-resistivity SrRuO 3 thin films on SiO 2 substrates. Therefore, in this study, the growth and characteristics of SrRuO 3 thin films deposited by radiofrequency magnetron sputtering on SiO 2 substrates without a buffer layer were investigated. It was found that the oxygen flow ratio in the growth ambient, post-deposition annealing temperature, and post-deposition annealing time are key parameters in realizing high-quality SrRuO 3 thin films. When SrRuO 3 thin films were deposited with a gas flow ratio of Ar:O 2 = 1:1.5 and subjected to post-deposition annealing in an oxygen ambient at 750 °C for 3 min, they exhibited an excellent resistivity of 148 μΩ-cm. This value is comparable to that of SrRuO 3 thin films epitaxially grown on single-crystal SrTiO 3 or LaAlO 3 substrates. • Prepared SrRuO 3 thin films by RF magnetron sputtering on SiO 2 without buffer layer. • O 2 flow ratio and post-annealing time and temperature important for low resistivity. • By process optimization, excellent resistivity of 148 μΩ-cm was obtained. • SrRuO 3 /SiO 2 thin films achieved resistivity similar to SrRuO 3 on SrTiO 3 and LaAlO 3. [ABSTRACT FROM AUTHOR]