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The magnetic and transport properties of Mn-doped ZnO thin films codoped with Sn are examined. Superconducting quantum interface device magnetometry measurements indicate that the films are ferromagnetic with an inverse correlation between magnetization and electron density as controlled by Sn doping.

SrTiO3 (STO) thin films were grown simultaneously via the metal organic chemical vapor deposition (MOCVD) technique on two different substrates: platinized sapphire and platinized TiO2/SiO2/Si. The thin films were analyzed for stoichiometry, crystallinity, surface roughness, and average grain size. Dielectric properties of the thin films such as dielectric constant, loss, and leakage current characteristics were measured and compared. We demonstrate that the MOCVD technique is an appropriate method for fabrication of STO thin films with excellent structural, microstructural, dielectric, and insulation properties. Comparative analysis of the films yielded an unexpected result that the thin film with a higher mismatch in thermal expansion coefficient between the substrate (Si) and the deposited STO film yielded a higher dielectric constant with respect to that of STO/sapphire. The dielectric loss for both films were similar (tan δ = 0.005 at 100 kHz), however, the leakage current for the film with a higher dielectric constant was three orders of magnitude higher. An explanation of these results is presented and discussed. [ABSTRACT FROM AUTHOR]

Isothermal (700 °C) ultraviolet annealing (UVA) processing of crystallized Ba0.60Sr0.40TiO3 (BST) thin films for exposure times up to 225 min films has been studied. The BST films, grown on PtSi wafers via the metalorganic solution deposition (MOSD) technique, were crystallized via conventional furnace annealing (CFA) prior to UVA treatment, and the effects of UV annealing time on the structural, dielectric, and insulation properties were evaluated. The experimental results demonstrated significantly improved structural, dielectric, and insulation properties for the UVA films. Specifically, lattice parameter contraction (toward that of bulk BST60/40) and a 20% reduction in loss were observed for the UVA treated films with respect to the CFA/control film. Leakage current characteristics were found to be the most sensitive characterization technique to access material property modification as a result of UVA exposure time. Specifically, the 225 min UVA exposure time resulted in a three-order of magnitude reduction in leakage current density compared to the CFA film, and the lowest value observed was 1.06 × 10-7 A/cm2 at E = 300 kV/cm. The useable tunability (tunability value at the maximum acceptable leakage current, 500 pA) was found to be elevated by a factor of two with respect to that of the CFA/control BST film (52.31%/UVA film vs. 18.5%/control film). It is suggested that the improved material properties are due to the mitigation of unwanted oxygen vacancies within the film after UV-annealing. A mechanistic model is presented and discussed. [ABSTRACT FROM AUTHOR]

Oxide semiconductors are attractive materials for thin-film electronics and optoelectronics due to compatibility with synthesis on large-area, inexpensive glass and flexible plastic substrate. However, development of thin-film electronics has been hampered by the limited number of semiconducting oxides that are p-type. Here, we report on the properties of zinc-cobalt-oxide (Zn–Co–O) films, deposited at room temperature using pulsed laser deposition, that exhibit p-type conduction. Films are deposited at room temperature in a background of oxygen using a polycrystalline ZnCo2O4 ablation target. The p-type conduction is confirmed by positive Seebeck coefficient and positive Hall coefficient. Both electrical resistivity and carrier density are dependent on oxygen background pressure used during deposition. Zn–Co–O films deposited in 50 mTorr oxygen pressure appear to be amorphous based on x-ray diffraction, and show an electrical conductivity as high as 21 S cm-1. Distinct rectifying current-voltage characteristics are observed for junctions between Zn–Co–O and n-type InGaZnO films, exhibiting a threshold voltage of ∼2.5 V. P-type Zn–Co–O appears promising for thin-film electronic device technology. [ABSTRACT FROM AUTHOR]

The magnetic and transport properties of Mn-doped ZnO thin films co-doped with P are examined. Superconducting quantum interference device magnetometry measurements indicate that the films are ferromagnetic with an inverse correlation between magnetization and electron density as controlled by P doping. In particular, under conditions where the acceptor dopants are activated leading to a decrease in free-electron density, magnetization is enhanced. The result is consistent with hole-mediated ferromagnetism in Mn-doped ZnO, in which bound acceptors mediate the ferromagnetic ordering. Increasing the electron density decreases the acceptor concentration, thus quenching the ferromagnetic exchange. This result is important in understanding ferromagnetism in transition metal doped semiconductors for spintronic devices. [ABSTRACT FROM AUTHOR]

The properties of zinc-cobalt-oxide (Zn-Co-O) films deposited at room temperature by using pulsed laser deposition that display p-type conduction are described. Distinct rectifying current-voltage characteristics are seen for junctions between Zn-Co-O and n-type InGaZnO films, which has displayed a threshold voltage, and P-type Zn-Co-O is promising for thin-film electronic device technology.

The residual stress and morphology of Pt electrodes were investigated using Ti and titanium oxide (TiOx) adhesion layers. Conventional or rapid thermal annealing (RTA) was used to compare the morphologies. The morphology depended on the substrate, adhesion layer, and annealing conditions, with large hillocks formed for electrodes incorporating Ti on Si. Electrode stacks utilizing TiOx adhesion layers resulted in residual stresses that were ∼50% less than those with Ti. Ba0.60Sr0.40TiO3 (BST) thin films were deposited onto several electrodes to investigate the integrity of the electrode/film heterostructures. Delamination or roughening of the film was observed depending on the adhesion layer. [ABSTRACT FROM AUTHOR]

We present the correlation between film fabrication conditions (crystallization temperatures), microstructure, and dielectric phase shift of Ba1-xSrxTiO3 (BST) thin films synthesized by metal organic solution deposition (MOSD) on sapphire substrates. The structure, microstructure, surface morphology, and composition of the films were assessed by glancing angle X-ray diffraction (GAXRD), atomic force microscopy (AFM), and Rutherford backscattering spectroscopy (RBS). The dielectric phase shift measurements were carried out using coplanar waveguide (CPW) test circuits over a frequency range of 2-18 GHz. Our results indicate that BST processed at 950°C achieved large relative phase shift response with low attenuation of the microwave signal. [ABSTRACT FROM AUTHOR]