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Al2O3 Films (al2o3 + film)
Selected AbstractsThermal Investigation of Al2O3 Thin Films for Application in Cutting Operations,ADVANCED ENGINEERING MATERIALS, Issue 7 2009Kirsten Bobzin Crystalline PVD ,-Al2O3 coatings offer great potential for use in high-speed cutting operations. They offer specific high temperature features, like high hot hardness and high oxidation resistance. However, the reasons for the high thermal stability of this system are not clearly understood. In this paper, the phase and oxidation stability of thin ,-Al2O3 films (as illustrated in the micrograph) are investigated. [source] Ionized physical vapor deposited Al2O3 films: Does subplantation favor formation of ,-Al2O3?PHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 7 2010K. Sarakinos Abstract The broad energy distributions of the condensing particles typically encountered in ion assisted vapor deposition techniques are often a drawback when attempting to understand the effect of the energetic bombardment on the film properties. In the current study, a monoenergetic Al+ beam generated by a filtered cathodic arc discharge is employed for the deposition of alumina (Al2O3) films at well defined Al+ ion energies between 4 eV and 200 eV at a substrate temperature of 720 °C. Structural analysis shows that Al+ energies of 40 eV or larger favor the formation of the thermodynamically stable ,-Al2O3 phase at the expense of other metastable Al2O3 polymorphs. The well defined ion energies are used as input for Monte-Carlo based simulations of the ion,surface interactions. The results of these simulations reveal that the increase of the Al+ ion energy leads to an increase in the fraction of ions subplanted into the growing film. These findings underline the previously not considered role of subsurface processes on the phase formation of ionized physical vapor deposited Al2O3 films. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electrical insulation properties of sputter-deposited SiO2, Si3N4 and Al2O3 films at room temperature and 400 °CPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 3 2009Hagen Bartzsch Abstract In this paper the breakdown field strength and resistivity of sputter-deposited Al2O3, SiO2 and Si3N4 layers are investigated in the temperature range between room temperature and 400 °C. All the investigated layers showed excellent insulation properties, even at elevated sample temperature. One example of industrial application is the deposition of electrical insulation layers onto the membranes of pressure sensors using cluster type sputter equipment [source] Interface of atomic layer deposited Al2O3 on H-terminated siliconPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 9 2006K. Y. Gao Abstract Al2O3 films 1 to 20 nm thick were deposited as alternative high-, gate dielectric on hydrogen-terminated silicon by Atomic Layer Deposition (ALD) and characterized by Synchrotron X-ray Photoelectron Spec-troscopy (SXPS), Fourier Transform Infrared (FTIR) absorption spectroscopy and admittance measure-ments. The SXPS results indicate that about 60% of the original Si,H surface bonds are preserved at the Al2O3/Si interface and this is confirmed by monitoring the Si,H stretching modes by FTIR spectroscopy in the Attenuated Total Reflection (ATR) mode both before and after ALD of Al2O3. The remaining 40% of Si,H bonds are replaced by Si,O bonds as verified by SXPS. In addition, a fraction of a monolayer of SiO2 forms on top of the Al2O3 dielectric during deposition. The presence of OH-groups at a level of 3% of the total oxygen content was detected throughout the Al2O3 layer through a chemically shifted O 1s component in SXPS. Admittance measurements give a dielectric constant of 9.12, but a relatively high density of interface traps between 1011 and 1012 cm,2 eV,1. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nanoparticle morphology in FeCo,Al2O3 granular films with tunneling giant magnetoresistancePHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2006Changzheng Wang Abstract A series of FeCo,Al2O3 granular films were prepared by a magnetron-controlled sputtering system. The tunneling giant magnetoresistance and nanoparticle morphology of FeCo particles in FeCo,Al2O3 granular films were directly determined utilizing a conventional four-probe method and TEM (HRTEM) observation, respectively. The results indicated that the tunneling giant magnetoresistance can reach a maximum of 6.9% at about 32.8 vol% FeCo particles, so far the highest value reported at room temperature and under an applied field of 12.5 kOe. Meanwhile, the sensitivity of TMR also reaches a maximum at about 32.8 vol% FeCo particles. In addition, TEM and HRTEM observation disclosed that FeCo,Al2O3 films consist of FeCo nanoparticles with bcc structure or amorphous FeCo phase dispersed in amorphous or crystalline Al2O3 matrix. For films with lower volume fraction of FeCo particles, the size distribution of FeCo particles satisfied a log-normal function. With increasing volume fraction of FeCo particles, the size distribution of FeCo particles deviated gradually from a log-normal function. Meanwhile, the average size of FeCo particles increased monotonically with increasing volume fraction of FeCo particles, leading to the fact that TMR can reach a peak value at a certain middle particle size. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] ALD growth of Al2O3 on GaAs: Oxide reduction, interface structure and CV performancePHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 2 2010H. D. Lee Abstract We have studied the effect of the trimethylaluminum (TMA) precursor on the reduction of surface "native" oxides from GaAs substrates using medium energy ion scattering spectroscopy (MEIS), X-ray photoelectron spectroscopy (XPS) and electrical measurements. Our data show that after one single TMA pulse a substantial part of the native oxide is reduced and an oxygen-rich aluminum oxide layer is formed. Al2O3 films grown with the normal atomic layer deposition cycles of TMA and water show that the growth rate of the Al oxide during this initial reduction of the native oxides is faster than the rate once this reduction is completed. Furthermore, the results of C-V measurements of Al2O3/GaAs grown under the same conditions along with post deposition annealing indicate a good quality interface. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Plasma-Assisted Atomic Layer Deposition of Al2O3 at Room TemperaturePLASMA PROCESSES AND POLYMERS, Issue S1 2009Tommi O. Kääriäinen Abstract A new design of plasma source has been used for the plasma-assisted atomic layer deposition (PA-ALD) of Al2O3 films at room temperature. In this PA-ALD reactor the plasma is generated by capacitive coupling directly in the deposition chamber adjacent to the substrate but can be separated from it by a grid to reduce the ion bombardment while maintaining the flow of radicals directly to the substrate surface. During the ALD cycle a mixture of nitrogen and argon was introduced into the reactor to act as a purge gas between precursor pulses and to facilitate the generation of a plasma during the plasma cycle. Sequential exposures of TMA and excited O2 precursors were used to deposit Al2O3 films on Si(100) substrates. A plasma discharge was activated during the oxygen gas pulse to form radicals in the reactor space. The experiments showed that the growth rate of the film increased with increasing plasma power and with increasing O2 pulse length before saturating at higher power and longer O2 pulse length. The growth rate saturated at the level of 1.78 Å·cycle,1. EDS analysis showed that the films were oxygen rich and had carbon as an impurity. This can be explained by the presence of bonds between hydrocarbons from the unreacted TMA precursor and excess oxygen in the film. ATR-FTIR spectroscopy measurements indicated a change in growth mechanism when the distance between the location of the radical generation and the substrate was varied. A similar effect was observed with the use of different plasma power levels. [source] Cyanide Sensing with Organic Dyes: Studies in Solution and on Nanostructured Al2O3 SurfacesCHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2008Nélida Gimeno Abstract The synthesis of two new azo phenyl thiourea compounds and their optical response to different anions is reported herein. Solution studies in methanol indicate that cyanide induces a colour change in these dyes (whereas no changes are observed in the presence of other anions, such as F,, Cl,, Br,, CH3COO,, H2PO4,, HSO4,). Interestingly, in DMSO these dyes are responsive not only to cyanide, but also to fluoride, acetate and dihydrogen phosphate. Each of these anions induces a different colour change. In the second part of the paper, we report the attachment of one of these dyes onto nanostructured TiO2 and Al2O3 films. The stability of these sensitised films to pH was studied and we concluded that the sensitised Al2O3 films are more robust, and hence, better than the TiO2 for anion sensing. The dye-sensitised Al2O3 films were immersed in solutions of different anions and their response studied. The films can detect cyanide down to 3,ppm in aqueous solution with relatively good selectivity over other anions. [source] | |||||||||||||