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High performance transparent thin-film transistors deposited on glass substrates and entirely processed at a low temperature not exceeding 150°C are presented and analyzed in this paper. Besides being based on an amorphous oxide semiconductor, the main innovation of this work relies on the use of sputtered multicomponent oxides as dielectric materials based on mixtures of Ta2O5 with SiO2 or Al2O3. These multicomponent dielectrics allow to obtain amorphous structures and low leakage currents while preserving a high dielectric constant. This results in transistors with remarkable electrical properties, such as field-effect mobility exceeding 35 cm2 V-1 s-1, close to 0 V turn-on voltage, on/off ratio higher than 106, and a subthreshold slope of 0.24 V decade-1, obtained with a Ta2O5: SiO2 dielectric. When subjected to severe current stress tests, optimized devices show little and reversible variation in their electrical characteristics. The devices presented here have properties comparable to the ones using plasma-enhanced chemical vapor deposited SiO2 at 400°C, reinforcing the success of this amorphous multicomponent dielectric approach for low temperature, high performance, and transparent electronic circuits. © 2009 The Electrochemical Society.

The authors report on the performance of polymer-based light-emitting diodes, LEDs, using amorphous zinc oxide-doped indium oxide, IZO, as anode. In particular, LEDs with poly[(2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] as electroluminescent layer and aluminium cathodes, show higher efficiency with this IZO anode (0.015 cd/A) than with indium-tin oxide (ITO) (0.010 cd/A). Inspite of the higher resistance of this IZO electrode, compared with ITO, the fact that it can be processed at lower temperatures and allows similar or even higher efficiency values for polymer LEDs make this material a good candidate for display and other optoelectronic applications. © 2009 Elsevier B.V. All rights reserved.

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The most important processes for the creation of S12+ to S14+ ions excited states from the ground configurations of S9+ to S14+ ions in an electron cyclotron resonance ion source, leading to the emission of K x-ray lines, are studied. Theoretical values for inner-shell excitation and ionization cross sections, including double-KL and triple-KLL ionizations, transition probabilities and energies for the de-excitation processes, are calculated in the framework of the multiconfiguration Dirac-Fock method. With reasonable assumptions about the electron energy distribution, a theoretical Kalpha x-ray spectrum is obtained, which is compared to recent experimental data.

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This paper describes the theoretical and experimental results achieved in optimizing the application of the series loaded series resonant converter for contactless energy transfer. The main goal of this work is to define the power stage operation mode that guarantees the highest possible efficiency. The results suggest a method to select the physical parameters (operation frequency, characteristic impedance, transformer ratio, etc.) to achieve that efficiency improvement. The research clarifies also the effects of the physical separation between both halves of the ferromagnetic core on the characteristics of the transformer. It is shown that for practical values of the separation distance, the leakage inductance, being part of the resonant inductor, remains almost unchanged. Nevertheless, the current distribution between the primary and the secondary windings changes significantly due to the large variation of the magnetizing inductance. An approximation in the circuit analysis permits to obtain more rapidly the changing values of the converter parameters. The analysis results in a set of equations which solutions are presented graphically. The graphics show a shift of the best efficiency operation zone, compared to the converter with an ideally coupled transformer. Experimental results are presented confirming that expected tendency.

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The coordination properties of the beta-keto phosphine ligands R(2)PCH(2)C(O)Ph (HL(1), R = i-Pr; HL(2), R = Ph), of the new acetamide-derived phosphine ligand (i-Pr)(2)PNHC(O) Me (HL(3)) and of Ph(2)PNHC(O) Me (HL(4)) have been examined towards Ni(II) complexes. Comparisons are made between systems in which the PCH(2) function of the ketophosphine has been replaced with an isoelectronic PNH group in amide-derived ligands, or the PCH functionality of phosphinoenolates with a PN group in phosphinoiminolate complexes. Furthermore, ligands HL(2) and HL(4) reacted with [(eta(5)-C(5)H(5))CoI(2)(CO)] to afford the phosphine mono-adducts [(eta(5)-C(5)H(5))CoI(2){Ph(2)PCH(2)C(O)Ph}] (1) and [(eta(5)-C(5)H(5))CoI(2){Ph(2)PNHC(O)Me}] (3), respectively, which upon reaction with excess NEt(3) yielded the phosphinoenolate complex [(eta(5)-C(5)H(5))CoI{Ph(2)PCH (center dot center dot center dot) under barC((center dot center dot center dot) under barO)Ph}] (2) and the phosphinoiminolate complex [(eta(5)-C(5)H(5))CoI{Ph(2)PN (center dot center dot center dot) under barC((center dot center dot center dot) under barO)Me}] (4), respectively. The complexes cis-[Ni{(i-Pr)(2)PN (center dot center dot center dot) under barC((center dot center dot center dot) under barO)Me}(2)] (6) and cis-[Ni{Ph(2)PN (center dot center dot center dot) under barC((center dot center dot center dot) under barO)Me}(2)] (7) were obtained similarly from NiCl(2) and HL(3) and HL(4), respectively, in the presence of a base. The phosphinoenolate complex [Ni{(i-Pr)(2)PCH (center dot center dot center dot) under barC((center dot center dot center dot) under barO) Ph}(2)] (5) exists in ethanol as a mixture of the cis and trans isomers, in contrast to cis-[Ni{(Ph(2)PCH (center dot center dot center dot) under barC((center dot center dot center dot) under barO)Ph}(2)], and the solid-state structure of the trans isomer of 5 was established by X-ray diffraction. The structures of the ligand HL3 and of the complexes 1, 3 in 3 center dot 3/2CH(2)Cl(2), 4, 6 and 7 have also been determined by X-ray diffraction and are compared with those of related complexes. Complexes 4, 6 and 7 contain a five-membered heteroatomic metallocyclic moiety, which is constituted by five different chemical elements. The structural consequences of the steric bulk of the P substituents and of the electronic characteristics of the P, O chelates are discussed.

This work analyzes the role of processing parameters on the electrical performance of GIZO (Ga2 O3: In2 O3:ZnO) films and thin-film transistors (TFTs). Parameters such as oxygen partial pressure, deposition pressure, target composition, thickness, and annealing temperature are studied. Generally, better devices are obtained when low oxygen partial pressure is used. This is related to the damage induced by oxygen ion bombardment and very high film's resistivity when higher oxygen partial pressures are used. Low deposition pressures and targets with richer indium compositions led to films with high carrier concentration, resulting in transistors with field-effect mobility as high as ∼80 cm2 Vs but poor channel conductivity modulation, becoming ineffective as switching devices. Nevertheless, it is demonstrated that reducing the GIZO thickness from 40 to 10 nm greatly enhances the switching behavior of those devices, due to the lower absolute number of free carriers and hence to their easier depletion. Annealing also proves to be crucial to control device performance, significantly modifying GIZO electrical resistivity and promoting local atomic rearrangement, being the optimal temperature determined by the as-produced films' properties. For the best-performing transistors, even with a low annealing temperature (150°C), remarkable properties such as μFE =73.9 cm2 Vs, onoff ratio≈7× 107, VT ≈0.2 V, and S=0.29 Vdec are achieved. © 2008 The Electrochemical Society.

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We have studied the properties of ZnO thin films grown by laser ablation of ZnO targets on (0 0 0 1) sapphire (Al2O3), under substrate temperatures around 400 8C. The films were characterized by different methods including X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and atomic force microscopy (AFM). XPS analysis revealed that the films are oxygen deficient, and XRD analysis with u–2u scans and rocking curves indicate that the ZnO thin films are highly c-axis oriented. All the films are ultraviolet (UV) sensitive. Sensitivity is maximum for the films deposited at lower temperature. The films deposited at higher temperatures show crystallite sizes of typically 500 nm, a high dark current and minimum photoresponse. In all films we observe persistent photoconductivity decay. More densely packed crystallites and a faster decay in photocurrent is observed for films deposited at lower temperature.

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