In this paper we describe the fabrication of oxide based electrodes that allow epitaxial growth of multilayer structures used to fabricate buried oxide-channel field effect transistors. The distinct characteristic of our buried electrodes is that they provide an etch stop layer which allow the opening of vias through the gate oxide using chemical etching. They can be patterned to define 1μm channel lengths and exhibit low contact resistance with channel materials such as YxPr1−xBa2Cu3O7-σ (YPBCO) or YBa2Cu3O7σ (YBCO).

Pt/Sr0.85Bi2.4Ta2O9/TiO2/Si structures were prepared with variation of the Sr0.85Bi2.4Ta2O9 (SBT) film thickness for MFIS-FET applications. After depositing TiO2 film of 10 nm thickness by reactive sputtering on Si(100) substrate as a buffer layer, SBT thin film of 210-400 nm thickness was prepared onto it by metal organic decomposition process. Regardless of the SBT film thickness, the Pt/SBT/TiO2/Si structures exhibited clockwise directional hysteresis, indicating well-defined ferroelectric switching behavior of the SBT films. While the memory window of the Pt/SBT/TiO2/Si MFIS structures increased with increasing the SBT film thickness, the maximum capacitance of the Pt/SBT/TiO2/Si MFIS structures decreased with increasing the SBT film thickness. The Pt/SBT(400 nm)/TiO2(10 nm)/Si structure exhibited a memory window of 1.3 V at ±5 V.

We present results of a comprehensive set of first-principles total-energy calculations of native and impurity-defect complexes in ZnO and use these results to elucidate the problems that occur in efforts to achieve p-type doping. The analysis naturally leads to new approaches that are likely to overcome the difficulties. The results provide detailed explanations of recent puzzling observations made in attempts to produce p-type ZnO.

ZnO:Al (ZAO) films were deposited on quartz substrates by dc magnetron reactive sputtering from a Zn target mixed with Al. The effect of substrate temperature and Al doping content on the structural, electrical and optical properties of ZAO films were investigated. It was observed that the (002) peak position of all films shifts to lower angle comparable to that of bulk ZnO due to the residual stress change with deposition parameters. The dependences of electrical properties such as resistivity, carrier concentration and Hall mobility on substrate temperature and Al doping content were measured. The minimum resistivity is 4.23×10−4 ω.cm with the carrier concentration of 9.21×1020 cm−3 and Hall mobility of 16.0 cm2v−1s−1. The visible transmittance of above 80% was obtained. The optical band gap was observed to increase with increasing carrier concentration. The possible mechanisms are discussed.

The aim of the present paper is to study low frequency (10 Hz - 10 kHz) noise in low dimensional colossal magnetoresistors (epitaxial CMR films). Two contributions in electrical fluctuations were observed: thermal noise, which depends on resistance and temperature, and excess part, which is determined by resistance fluctuations and are mostly related to film microstructure. For films, thicker than the critical thickness, excess noise spectra has 1/fα dependence with α = 1 ± 0.2. In films thinner than the critical one there are random telegraph like signals (TLS) with Lorentzian spectra appear on the background of 1/f noise. Noise spectroscopy reveals the relaxation process in 4.2 nm thick film has thermally activated character with an energy gap of 20 meV at temperatures below 156 K and 78 meV at T > 156 K.

Indium tin oxide (ITO) films deposited on polyester substrates are a key material in the development of two exciting technologies, touchscreens and flexible liquid crystal displays. The new generation “plastic” displays and touchscreens must be flexible and robust, have excellent optical properties, and be inexpensive. We report on the mechanical and electrical reliability of ITO on a polyethylene terephthalate substrate (PET). We show that the mechanical behavior of the ITO film is dominated by the properties of the substrate and that the deformation of the substrate is mapped by the crack patterns in the ITO. This is most strongly evidenced in the simulated wear of a touchscreen where failure after >50000 pen strokes is primarily due to cracking of the ITO as a result of increased substrate deformation over time. In addition the mechanical reliability of the ITO layer is dependent on the film thickness. Cracking was observed in a 105 nm thick ITO film at a strain of 0.022 and for a 16.8 nm thick film at 0.003. The thickness and hence sheet resistance of the film effectively limits the maximum allowable deformation of the substrate and must be considered in the design of suitable display and touchscreen devices. In addition we report on the change in resistance with time-at- temperature and relate this to the shrinkage of the substrate.

We prepared colossal magnetoresistive La0.8Sr0.2MnO3 thin films on the MgO, SrTiO3 and LaAlO3 single crystal substrates using KrF excimer pulsed laser ablation technique. The structural and electrical properties of the La0.8Sr0.2MnO3 thin films which were strained by the lattice mismatch are reported. The in-plane lattice mismatch between the La0.8Sr0.2MnO3 and MgO, SrTiO3 and LaAlO3 substrates are -7.8 %, -0.5 % and +2.3 %, respectively. The X-ray diffraction spectra of the films exhibited c-axis orientation. In the case of the La0.8Sr0.2MnO3 / LaAlO3 thin films with thickness over 100 nm, the divided (00l) peaks were observed. The surface morphology and transport property of the strongly stressed La0.8Sr0.2MnO3 / LaAlO3 were different from those of La0.8Sr0.2MnO3 / MgO and La0.8Sr0.2MnO3 / SrTiO3thin films.

This paper reports the properties of undoped CdO films and CdO films doped with the group VII element F and the group IV element Sn. The CdO films are made by low-pressure chemical-vapor deposition. We observe that undoped CdO films can achieve a carrier concentration of 1021 cm−3, apparently by controlling the intrinsic defect. However, the electron mobility of these films is only around 2 cm2 V−1 s−1. With fluorine doping, an electron mobility of ∼260 cm2 V−1 s−1 has been achieved. However, low carrier concentration results because of the low solubility of F in CdO film. CdO films doped with both Sn and F demonstrate carrier concentrations of 1021 cm−3 and reasonable electron mobilities of around 20 cm2 V−1 s−1. Due to the small effective electron mass of CdO, a large Burstein-Moss shift is observed for films with high carrier concentration. The shift enables the fundamental absorption edges of undoped CdO films to reach 3.0 eV and 3.3 eV for films doped with both Sn and F.

Highly textured transparent conducting ZnO:Al thin films have been prepared by r.f. magnetron sputtering. The films were deposited on polyester (Mylar type D, 100 µm thickness) and glass substrates at room temperature. Surface stylus profiling, X-ray diffraction, scanning electron microscopy, transmission electron microscope and Hall effect measurements as a function of temperature have been used to characterize the produced films. The samples are polycrystalline with a hexagonal wurtzite structure and a strong crystallographic c-axis orientation (002) perpendicular to the substrate surface (columnar structure). The ZnO:Al thin films with a resistivity as low as 3.6×10−2 µcm have been obtained, as deposited.

We have studied the growth of magnesium oxide using ion-beam assisted deposition (IBAD) to achieve (100) oriented, bi-axially textured films with low mosaic spread, for film thicknesses of 10 nm on silicon substrates. We have refined the process by using reflected high-energy electron diffraction (RHEED) to monitor the growth of IBAD MgO films and found that the diffracted intensity can be used to determine (and ultimately control) final in-plane texture of the film. Here we present results on our work to develop the use of real-time RHEED monitoring to deposit well-oriented IBAD MgO films. The results have been corroborated with extensive grazing-incidence X-ray diffraction (GID). Results of these analyses have allowed us to deposit films on metallic substrates with in-plane mosaic spread less than 7°.

Single-phase, spinel zinc stannate (ZTO = Zn2SnO4) thin films were grown by rf magnetron sputtering onto glass substrates. Uniaxially oriented films with resistivities of 10−2 -10−3 ωcm, mobilities of 16 - 26 cm2/V-s, and n-type carrier concentrations in the low 1019 cm−3 range were achieved. X-ray diffraction peak intensity studies established the films to be in the inverse spinel configuration. 119Sn Mössbauer studies identified two octahedral Sn sites, each with a unique quadrupole splitting, but with a common isomer shift consistent with Sn+4. A pronounced Burstein-Moss shift moved the optical bandgap from 3.35 eV to as high as 3.89 eV.

Density-of-states effective mass, relaxation time, mobility, Fermi energy level, and a scattering parameter were calculated from transport data. Effective-mass values increased with carrier concentration from 0.16 to 0.26 me as the Fermi energy increased from 0.2 to 0.9 eV above the conduction-band minimum. First-order nonparabolic conduction-band theory was applied to extrapolate a bottom-of-the-band effective mass of 0.15 me. Calculated scattering parameters and temperature-dependent transport measurements correlated well with ionized impurity scattering with screening by free electrons for highly degenerate films.

We have prepared lanthanum strontium cobalt oxide (La0.50Sr0.50CoO3; LSCO 50/50) and lanthanum strontium cobalt nickel oxide (La0.50Sr0.50Co0.50Ni0.50O3; LSCNO) as candidate transparent electrodes for use in a shutter-based infrared sensor protection device. The shutter device requires that the electrode be transparent (80% transmission) and have moderate sheet resistance (300 ω/sq.). Because of the effects of film thickness on intrinsic material properties, such as resistivity and extinction coefficient, and simple engineering issues (i.e., the relationship between film thickness, resistance and transmission), films of various thicknesses were prepared to achieve an optimal balance of electrical and optical performance. van der Pauw measurements and FTIR spectroscopy were used to study thin film properties. The best LSCO films prepared demonstrated electrical (438 ω/sq.) and optical (68% transmission at 8 µm) properties that did not meet the target property goals for this application. However, the LSCNO films (of optimal thickness) offered performance (323 µ/sq. and 73% transmission) close to the device requirements.

There is great interest in forming nanoscale structures through thermodynamically driven self-assembly processes. Self-assembled processes hold the promise of enabling the creation of complex, next-generation device architectures that rely on the intrinsic ability of the system to organize itself into ordered patterns. This is in contrast to the artificially ordered schemes, such as those currently used in integrated circuits. Many inorganic systems display microstructural evolution that resemble self-assembled processes, for example spinodal decomposition in alloys, dendrite formation in melts, and martensitic twins in metallic and ceramic alloys, where the assembly process is driven by thermodynamic and kinetic considerations. In this paper, we report on the self-assembly of nanometer-scale hillocks of conducting palladium oxide. We report the formation of periodic arrays of self-assembled hillocks upon oxidation of Pd films. The PdO2 hillocks are referred to as “tips” due to their significantly large height (∼ 1νm) and conical shape. The tips are spaced ∼2.5μm apart and tip height is dependent on the film thickness, granularity and annealing conditions. The height and size of the PdO2 tips increased and their distribution became narrow with increasing film thickness. We show that these structures can be fabricated on a number of substrates including silicon, glass, and various ceramic substrates.

A detail kinetic analysis was performed on the PbTiO3 phase formation reaction occurring via PbO-TiO2 diffusion couple experiments. The diffusion model of Pb2+ and O2− ions was used to derive the kinetics equation of PbTiO3 phase formation reaction. From the parabolic kinetics between the thickness of PbTiO3 layer and time, the reaction rate constant for PbTiO3 formation was determined to be a function of the average diffusion coefficient of Pb2+ ions. By substituting the diffusion couple experimental results into the present kinetics equation, average diffusion coefficient values of Pb2+ ions in PbTiO3 layer were calculated according to temperature values. The activation energy value for the diffusion of Pb2+ ions was estimated for PbTiO3 formation using Arrhenius plot and the equation for the diffusion coefficient of Pb2+ ions was determined.

Interfacial reactions between SrRuO3 films and Si substrate were investigated by using field emission-transmission electron microscopy (FE-TEM). The compositional and structural variations across the interface were analyzed by using energy dispersive X-ray spectroscopy (EDS) and diffraction with an electron probe in 0.5 nm in diameter. Two constituent binary oxides of SrRuO3, i.e. SrO and RuO2, were found to react differently on Si surface: 1) SrO in stable contact with Si, and 2) RuO2 in unstable contact. The reduction of SrRuO3 to elemental Ru by Si is believed to be most favorable candidate for the reaction leading to the unstable contact of SrRuO3 on Si.

Epitaxial La0.67Ca0.33MnO3(LCMO) films have been grown by pulsed laser deposition technique on three single crystal substrates: LaAlO3, SrTiO3, and NdGaO3 having lattice mismatch with LCMO film of + 1.26 %, - 0.9 %, and + 0.18 %. We found the transport colossal magnetoresistive (CMR) properties were improved with the reduction of a film/substrate mismatch. Processing conditions for LCMO film on NdGaO3substrate were optimized as well as post-annealing process was employed to achieve a superior temperature coefficient of resistivity TCR = 35 %K−1 and the magnetoresistance MR = 66 % at 7 kOe. To our knowledge, these are the record CMR parameters achieved so far.

The origin of the exchange bias between a ferro- and an antiferromagnet still is not fully resolved. Many structural parameters such as film thickness, roughness, domain size, domain walls, strain, dislocations, and surface defects play a role. To disentangle their individual contributions, one must correlate each of these structural effects with the exchange bias. Here we report our first such attempts using thin films of the antiferromagnetic orthoferrite LaFeO3 grown by molecular beam epitaxy. We investigate how the epitaxial relationship and strain affect the domain configuration as well as their size and orientation. Next, we explore how these different domains can pin ferromagnetic domains in exchange-coupled systems. We conclude that decreasing the domain size of the antiferromagnet leads to a higher exchange bias. The highest exchange bias was obtained for LaFeO3 films on MgO substrates.

A transparent oxide semiconductor with delafossite structure, CuInO2, was found to exhibit both p-type and n-type conduction by doping of an appropriate impurity and tuning of proper film-deposition conditions. Thin films of Ca-doped or Sn-doped CuInO2 were prepared on -Al2O3 (001) single crystal substrates by pulsed laser deposition method. The films were deposited at 723 K in O2 atmosphere of 1.0 Pa for the Ca-doped films or 1.5 Pa for the Sn-doped films. The positive sign of the Seebeck coefficient demonstrated p-type conduction in the Ca-doped films, while the Seebeck coefficient of the Sn-doped films was negative indicating n-type conductivity. The electrical conductivities of Ca-doped and Sn-doped CuInO2 thin films were 2.8×10−3 S·cm−1 and 3.8×10−3 S·cm−1, respectively, at 300 K. The optical band gap of each film was estimated to be ∼3.9 eV. Since CuInO2 exhibited bipolarity in electrical conduction, transparent p-n homojunctions based on CuInO2 were fabricated on (111) surface of yttria-stabilized zirconia single-crystal substrates. The structure of the diode was In2O3:Sn / n-CuInO2:Sn / p-CuInO2:Ca / In2O3:Sn electrode on the substrate. The contact between the n-and p-type CuInO2 semiconducting oxides was found to be rectifying. The turn-on voltage was ∼1.8 V.

Ba1−xCaxTi1-yZryO3 materials have very high dielectric constant (up to 30,000) in the bulk form. In this paper, we are presenting the electrical and structural characteristics of undoped and 0.4% Mg-doped Ba0.96Ca0.04Ti0.84Zr0.16O3 (BCTZ) thin films on Pt/Ti/SiO2/Si substrates. The BCTZ films were deposited by spin on metal-organic decomposition method and annealed at a temperature 600-900°C in oxygen environment. The annealed thin films were characterized by X-ray diffraction. The electrical characteristics of the annealed thin films were analyzed by capacitance–voltage and current–voltage measurements. The as-annealed thin films were post- annealed in nitrogen and oxygen environments and the effect of post-annealing on their electrical characteristics were also presented in conjunction with 0.4% Mg doping effect of BCTZ thin films for possible high dielectric constant material applications.

The deposition of ITO onto glass substrates at room temperature results in a metastable amorphous phase that undergoes crystallization at remarkably low homologous temperatures (T/Tm<0.2). We have evaluated ITO film stress in the as-deposited condition and during crystallization of 200 nm thick films isothermally heated at 250°C. To explore the effect of stoichiometry on the amorphous structure, ITO films were deposited under low, optimum, and high (0, 0.1, and 2 vol %, respectively) oxygen partial pressures. In this report we have correlated changes in stress with changes in the electron transport characteristics (hall mobility and carrier density) and film microstructure.