This study shows the excellent heat resistance of hydrogen doped ZnO:Ga (GZO) films successfully fabricated by stacking a GZO protection film. The poor heat resistance of hydrogen doped GZO films caused by the departure of hydrogen from films after the RTA treatment exceeded 400 degrees C results in an increase in the resistivity. It means they are not suitable for thin film practical application processing with elevated temperatures. The electrical properties can be seen that the resistivity and carrier concentration of the GZO/GZO:H films remains nearly stable up to the annealing temperature of 600 degrees C, and they maintain low resistivity below 5.6 x 10(-4) Omega-cm. (C) 2012 The Electrochemical Society. [DOI:10.1149/2.021204esl] All rights reserved.
This contribution presents the results of an X-ray photoelectron spectroscopy (XPS) study aimed at gaining further insight into the interactions between Si, Ti, TiN, and Pt. Our approach involves the sequential deposition of Ti, TiN, and Pt onto a clean, well-characterized Si(111) surface, a substrate known to react with Pt . These depositions were carried out in situ under ultra-high vacuum (UHV) in a chamber equipped to perform angle-resolved XPS (ARXPS) and various other types of characterization. It will be shown that layers of TiN only ca. 1 nm thick are sufficient to prevent interdiffusion between Pt and Si.
Lithium garnet oxides of the composition series Li7−xLa3Zr2−xTaxO12 (x = 0−2) were synthesized by the solid state reaction and characterized by the powder X-ray diffraction and the impedance spectroscopy. Single cubic phases were obtained between x = 0.2 and 2, while the end-member Li7La3Zr2O12 exhibited a tetragonal phase. The lattice parameters of the cubic series followed the Vegard’s law. The maximum bulk (9.6 × 10−4 S/cm) and total (6.9 × 10−4 S/cm) conductivities were achieved at x = 0.3 and x = 0.2, respectively at room temperature. Electrochemical tests with a hybrid solid|liquid electrolyte configuration were performed to evaluate the electrochemical performance of the solid electrolytes. © 2012 The Electrochemical Society. [DOI: 10.1149/2.024205esl] All rights reserved.
GaN-based LEDs were fabricated on patterned-sapphire substrates with various pyramidal-pattern coverage percentages (31-81%). Three distinguish stages are observed in the behavior of the light out-put power against coverage percentage. By etching-pit density measurement, dislocation density is found to be independent with coverage percentage. The light extraction efficiency (LEE) should be the main mechanism for the enhancement in the light out-put power. LEE would be enhanced, when the pattern coverage is less than 39% or over 67%. The light extraction efficiency remains similar, when the pattern coverage in between 39% similar to 67%. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.018203esl] All rights reserved.
We investigated the thermal stability of ZnO:H films deposited by radio frequency magnetron sputtering at room temperature. The lowest resistivity obtained for a ZnO:H film was 1.99 x 10(-3) Omega-cm with a 10% H-2/Ar flow ratio. The increase in the H-2/Ar flow ratio during deposition plays an important role in producing better thermal stability ZnO:H films as the result of the increase in the percentage of substitutional Ho in the ZnO:H films. The resistivity of the ZnO:H film with 50% H-2/Ar flow ratio can be reduced from 3.49 x 10(-3) Omega-cm to 2.35 x 10(-3) Omega-cm after heat treatment to 300 degrees C. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.022201esl] All rights reserved.
Cu1.95Se films were fabricated by electrophoresis deposition (EPD) with Cu1.95Se nanocrystals synthesized by the one-pot solution-phase process. The resistivity (7.64 x 10(-3) Omega-cm), carrier concentration (1.07 x 10(20) cm(-3)), and mobility [7.62 cm(2)(vs)(-1)] of Cu1.95Se film fabricated at an EPD voltage of 30 V were an improvement on that of Cu1.95Se film fabricated at an EPD voltage of 70 V, which can be attributed to the higher density (packing density = 52.4%) of the film fabricated at 30 V. The EPD-growth method has high potential for fabrication of non-vacuum, room-temperature-grown Cu2-xSe films. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.001201esl] All rights reserved.
Environment-friendly 5,10,15,20-Tetraphenylporphyrin (TPP) was synthesized and its inhibition effect on pure Mg in 0.05 wt.% NaCl solution was studied by means of electrochemical measurement and immersion corrosion test. Results indicate that TPP has high inhibition efficiency for Mg. Based on infrared and ultraviolet spectroscopic analyses, it is believed that TPP molecules can chelate with Mg and form an insoluble TPP-Mg complex film on the surface to retard the corrosion of pure Mg. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.021206esl] All rights reserved.
In this study, a high breakdown voltage (V-BR) enhancement-mode (E-mode) MgxZn1-xO channel thin-film transistor (TFT) was realized using a gadolinium oxide (Gd2O3) gate insulator and CF4 plasma treatment technologies. The threshold voltage (V-T) for conventional Gd2O3/MgxZn1-xO TFTs was -2.8 V and this value was adjusted to + 0.1V after nine minutes of CF4 plasma treatment beneath the gate regime. X-ray photoelectron spectroscopy (XPS) results indicated that the fluorine atoms reduced the number of oxygen vacancies in MgxZn1-xO channel, resulting in an extreme low carrier concentration beneath the gate region. Additionally, this E-mode TFT had favorable surface roughness and low interface state density. (C) 2011 The Electrochemical Society. [DOI: 10.1149/ 2.004202esl] All rights reserved.
The effect of nitrogen content on compensation of N-related defects in Al-N codoped Mg0.05Zn0.95O films was investigated. The result shows that the main N-related defect is N-O at low N content which contributes to p-type conductivity. When the N content increases, N-O acceptors combine with N-i to form low-energy substitutional diatomic molecules on the O sites, i.e. (N-2)(O) donors. The net hole concentration decreases because holes are compensated by electrons. The conduction finally becomes n-type. The compensation of N-O acceptors by (N-2)(O) explains the difficulty to achieve high p-type conduction by N doping in ZnO-type materials. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.015205esl] All rights reserved.
P-type CuInSe2 (CIS) thin films were prepared from aqueous solution by photoelectrochemical deposition (PED). The linear sweep photovoltammetry was employed to investigate the electrochemical behavior of PED and choose the suitable deposition potential. Comparing with conventional electrochemical deposition (CED), it is found that PED process can increase the deposition rate, promote the incorporation of indium into deposited films, improve the homogeneity and compactness of film morphology, inhibit the growth of undesired Cu-Se phases and enhance the photocurrent response in photoelectrochemical test. These characters are beneficial to high efficiency CIS solar cell fabrication. (C) 2012 The Electrochemical Society. [DOI:10.1149/2.007204esl] All rights reserved.
We demonstrate a novel metal stanogermanide contact metallization process for high mobility germanium-tin (GeSn) channel MOSFETs. The multi-phase nickel-platinum stanogermanide [Ni(GeSn)+Pt-x(GeSn)(y)] contacts are formed by reacting Ni-Pt alloy with Ge0.947Sn0.053 alloy, which is epitaxially grown on Ge (100) substrate by solid source molecular beam epitaxy (MBE). Compared with nickel stanogermanide [Ni(GeSn)] contacts, the Pt-incorporated contacts, i.e. [Ni(GeSn)+Pt-x(GeSn)(y)], exhibit enhanced thermal stability in a wide range of formation temperatures and have superior surface morphology even after thermal processing. The proposed contacts are attractive for the integration in high mobility GeSn MOSFETs. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.014206esl] All rights reserved.
We report on the unipolar resistive switching (RS) phenomenon in yttrium oxide (Y2O3) metal-insulator-metal structures. The RS behavior for Y2O3 shows a superior ON/OFF resistance ratio of greater than 106 and good memory retention reliability performance of at least 10(6) seconds at room temperature. By adding a thin yttrium (Y) layer to form a Y-Y2O3 bilayer structure, a reduction in the RESET current by two orders of magnitude is achieved, which is advantageous in reducing the total switching energy consumption for resistive random access memory application. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.008203esl] All rights reserved.
Controllable and selective synthesis is essential for many potential applications of gold nanocrystals in nanodevice manufacturing. In the current article, a hybrid technology that integrates electrodeposition with dielectrophoresis is reported, demonstrating the controllable fabrication of nanostructures with desirable dimensionality and morphology, such as particles, aligned nanowires, networks, coral-like morphologies, and three-dimensional branched nanocrystals on a scaffold. The current experiments and calculations reveal the dependence of morphology on electrode geometry and electric field parameters. The proposed templateless and facile technology offers great potential for the rational synthesis of other metallic nanomaterials with controllable morphology for advanced functional applications. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.017202esl] All rights reserved.
We report on the improvement of the thermal stability of Ag ohmic contacts for high-power GaN-based vertical light-emitting diodes (LEDs) using a Zn capping layer. The 20-nm-thick Zn capping layer suppresses agglomeration by forming ZnO. Blue LEDs fabricated with the Ag/Zn contacts give higher output power than do LEDs with Ag only contacts. LEDs with the 500 degrees C-annealed Ag/Zn contacts exhibit 34% higher output power (at 20 mA) than LEDs with the 500 degrees C-annealed Ag only contacts. X-ray photoemission spectroscopy measurements are performed to describe the temperature dependence of the electrical properties of LEDs with the Ag/Zn contacts. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.002205esl] All rights reserved.
1-Ethyl-3-methylimidazolium hydrogensulfate (EMIHSO4), an ionic liquid (IL), was investigated as both liquid and solid electrolyte for electrochemical capacitors (ECs). The high resistivity of EMIHSO4 could be overcome by developing a polymer-EMIHSO4 electrolyte. This polymer electrolyte, preferable for environmental and safety reasons, exhibited better performance than liquid EMIHSO4. ECs fabricated using this polymer electrolyte demonstrated a cell voltage window of 0-1.5 V and very stable cycle life. Good high-rate response up to 1 V/s and a time constant of 1 s were observed through cyclic voltammetry and impedance analyses, respectively. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.005202esl] All rights reserved.
MnO/MnSiO3-based layers were formed on porous SiCOH low-k dielectrics by Chemical Vapor Deposition (CVD) of Mn from Bisethylcyclopentadienyl manganese. The oxide phase formation is driven by the moisture desorbing from the low-k films. The silicate phase is defined by silanol groups chemisorbed on the low-k surface. The experimental results suggest that formation of thin Mn-based copper diffusion barrier (pore sealing) by CVD is limited to dielectrics having a pore size smaller than the Mn precursor molecules. In the case of larger pore sizes, Mn is deposited inside the dielectric on the pores surface and the layer cannot be a diffusion barrier. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.006206esl] All rights reserved.
A method allowing the electrical characterization of ionic conducting films is described. This method is based on the calibration of the electrically active surface of a platinum micro-electrode. This method allows a significant decrease of instrumental or parasitic effects, the observation of dielectric relaxations at high temperature, the characterization of imperfectly tight layers, and gives an alternative to paint or sputtered Pt layer current collectors. (C) 2012 The Electrochemical Society. [DOI:10.1149/2.029204esl] All rights reserved.
Carbon coated LiFePO4 was modified with Sr0.85Ce0.15CoO3-delta via a suspension mixing process followed by heat treatment. An integrate network formed by Sr0.85Ce0.15CoO3-delta and carbon was found on the surface of LiFePO4 particles by high resolution transmission electron microscopy. The co-coating layers alleviated the charge-transfer impedance and facilitated the lithium-ion diffusion. Consequently, the discharge capacity was significantly improved especially at high rates. The sample coated with 3 wt% Sr0.85Ce0.15CoO3-delta showed a high capacity of 94 mAh g(-1) compared with that of uncoated sample (65 mAh g(-1)) at 5C. (C) 2011 The Electrochemical Society. [DOI: 10.1149/2.001202esl] All rights reserved.
