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Thin film transistors (TFTs) with In and Ga-free multicomponent Zn-Sn-Zr-O (ZTZO) channel layers were fabricated using the cosputtering approach. The incorporation of ZrO2 into the Zn-Sn-O (ZTO) films increased the contact resistance, which led to the degradation of the transport properties. In contrast, the threshold voltage shift under negative bias illumination stress (NBIS) was largely improved from -12.5 V (ZTO device) to -4.2 V (ZTZO device). This improvement was attributed to the reduction in the oxygen vacancy defects in the ZTZO film, suggesting that the photoinduced transition from VO to VO2+ was responsible for the NBIS-induced instability. [ABSTRACT FROM AUTHOR]

The authors measured magnetization hysteresis curves and used magneto-optical imaging to visualize the flux distributions in superconducting MgB2 films in order to study dendritic flux avalanches. The flux avalanches are found to disappear above some upper threshold field that is typically ∼1 kOe, but strongly depends on the film width. If the film is made wider, this threshold field first increases and then tends to saturate. This behavior is quantitatively explained using a thermomagnetic model for the dendritic avalanches and taking into account the field dependence of Jc. The results demonstrate that patterning superconducting films into narrow strips substantially increases the range of magnetic fields for which they can be used for applications. [ABSTRACT FROM AUTHOR]

Current conduction mechanisms of an atomic-layer-deposited Al2O3 gate on n-type 4H SiC have been systematically investigated, analyzed, and reported in this letter. It has been revealed that space charge limited, Poole-Frenkel (PF) emission, combination of PF emission and Fowler-Nordheim tunneling are the dominate current conduction mechanisms in the dielectric. Besides, Schottky emission has also been proposed as a possible leakage path at temperature beyond the investigated range. A relationship among the conduction mechanism, temperature, and applied electric field has been presented. [ABSTRACT FROM AUTHOR]

The effects of the isoelectronic Al doping of epitaxial GaN films grown by metalorganic chemical vapor deposition on a (0001) Al2O3 single crystal substrate were investigated. It was found that the threading screw and edge dislocation densities of the GaN film decreased to less than half of that of the undoped GaN film up to Al doping concentration of 0.45%. The in-plane and out-of-plane strains were simultaneously reduced with the decrease in dislocation density as a result of the solution hardening effect. Accordingly, the electron mobility of the 0.45% Al-doped GaN film (524 cm2/Vs) was greatly improved compared to that of the undoped GaN film (178 cm2/Vs). However, the threading dislocation densities and strains were increased at a 0.64% Al concentration, and the electron mobility decreased accordingly. Therefore, the improvement in the electron mobility by Al doping up to 0.45% is the result of a decrease in the threading dislocation density and not a decrease in the number of point defects (Ga-site vacancy) as suggested earlier [Lee et al., Appl. Phys. Lett. 83, 917 (2003)]. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We measured the superconducting critical current densities (J[sub c]) from the magnetization hysteresis (M–H) loop for Au-coated MgB[sub 2] thin films. The purpose of this experiment was to determine whether the vortex avalanche phenomenon which suppresses the J[sub c] for low temperature (T<15 K) and low field (H≤1000 Oe) could be cured by gold deposition. This avalanche, called flux noise, has been a headache in applications of MgB[sub 2] thin films. Fortunately, the flux noise in the M–H loop is suppressed with increasing Au-film thickness and finally disappears when the thickness of the gold becomes 2.55 μm. We found a way to remove one obstacle for applications of MgB[sub 2] thin films as an superconducting device. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The minority carrier (electron) capture process and the interface trap density of a TiN/Al[sub 2]O[sub 3]/p-Si metal-oxide-semiconductor capacitor were examined by deep level transient spectroscopy (DLTS). It was found that the activation energies of the large peaks detected at higher temperatures with gate bias voltages of 1.8, 1.5, 1.3, and 1.1 V were 0.19, 0.24, 0.29, and 0.37 eV, respectively. These energies were related to the electron-capture process from the conduction band by interface states in the upper half of the Si band gap. The interface state passivation effect of postannealing in a hydrogen ambient was studied from the minority carrier capture process and the usual DLTS signals. The D[sub it] at an energy of 0.35 eV from the valence bandedge decreased from 1 × 10[sup 12] cm[sup -2] eV[sup -1] at the as-fabricated state to 4 × 10[sup 11] cm[sup -2] eV[sup - 1] after H[sub 2] annealing at 450 °C. It was also found that the D[sub it] at an energy of 0.3 eV from the conduction bandedge decreased to the same amount by the same annealing process. [ABSTRACT FROM AUTHOR]

Pb(Zr, Ti)O[sub 3] (PZT) thin films were deposited on Pt/Ti and Pt/IrO[sub 2] electrode stacks with various Pt thicknesses (30-200 nm) by a sol-gel process. The sputter-deposited Pt films showed a (111)-preferred texture irrespective of the thickness. However, a high-resolution x-ray diffraction study of the Pt films showed that the films were composed of three kinds of grains with slightly different lattice parameters. The grains with a bulk-like lattice parameter grew with increasing Pt thickness, which was accompanied with an improvement in the crystalline quality. Accordingly, the crystallization and ferroelectric behavior of the 100-nm-thick PZT films improved with increasing Pt film thickness. However, the PZT films on the Pt/IrO[sub 2] electrode showed a deteriorated ferroelectric performance due to the outward diffusion of the Ir (O) onto the Pt surface, which increases the depolarizing field and amount of charge injection by the formation of a conducting phase. [ABSTRACT FROM AUTHOR]

The electrical conduction behavior of sputter-grown (Ba, Sr)TiO[sub 3](BST) thin films having IrO[sub 2] electrodes were studied under the assumption of a fully accumulated film. In the film-thickness range studied (40-80 nm), the dielectric constants and their electric field dependencies were found to be independent of the film thickness. Contrary to similar BST films grown on Pt electrodes, the leakage current density decreased with increasing film thickness at a given field. The phenomena were explained from the electric-field depression effect inside the film due to the accumulated negative space charges in the films. The leakage current conductions were controlled by the Poole-Frenkel mechanism in the low field whereas it changed to thermionic field emission in the high-field region. The dielectric constant obtained from the Poole-Frenkel fitting was approximately 300, which was in a qualitative agreement with the value obtained from the low-frequency capacitance measurement. The calculated interfacial potential-barrier height at zero volt and effective mass of electrons were 1.03 eV and 0.06m[sub 0], respectively, from the thermionic field emission fittings. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The longitudinal resistivity (ρ[sub xx]) and Hall coefficient (R[sub H]) were measured for MgB[sub 2] sintered under high pressure. We found that R[sub H] is positive like cuprate high-T[sub c] superconductors, and decreases as the temperature increases for 40 K

(Ba,Sr)TiO[sub 3] (BST) thin films were prepared on Pt/SiO[sub 2]/Si substrates by the pulse injection chemical vapor deposition (CVD) process, in which the vapor of precursors was allowed to flow periodically into the reaction chamber. The dielectric constants of BST thin films, which were deposited by pulse injection CVD, were slightly higher than those of continuous BST thin films. In addition, the leakage currents were lowered by an order of magnitude. 35 nm thick BST thin films, deposited by pulse injection CVD and postannealed at 600 °C under O[sub 2] atmosphere for 30 min, showed a SiO[sub 2] equivalent thickness of 0.64 nm, a dielectric dissipation factor less than 0.5%, and a leakage current density of 1×10[sup -7] A/cm[sup 2] at +1.5 V bias. The improvement in the electrical properties of pulse BST thin films seems to originate from better crystallinity and less carbon contamination during the pulse deposition process.© 1998 American Institute of Physics. [ABSTRACT FROM AUTHOR]