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Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films

Issue 1 • Date Jan 2013

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Displaying Results 1 - 25 of 54
  • Interface layer in hafnia/Si films as a function of ALD cycles

    Page(s): 010601 - 010601-6
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    A systematic angle resolved x-ray photoelectron spectroscopy study of the structure of hafnia films grown on silicon with atomic layer deposition (ALD) is presented. The hafnium precursor employed was tetrakis dimethyl amino hafnium with water as the oxidant agent. The number of ALD cycles ranged from 3 to 25. The Hf 4f spectrum shows two components 0.47 eV apart, one associated with hafnia (17.6 eV) and the other (18.1 eV) with a hafnium silicate interface layer. The composition of the interface layer, HfxSi1-xOy, evolves continuously from silicon-rich (x = 0.1 for 3 ALD cycles) to hafnium rich (x = 0.75 for 25 ALD cycles). The binding energy difference between the Hf 4f components associated with the silicate and hafnia changes very little with the silicate composition. The binding energy of the Si4+ component, which is associated with the silicate, varies from 3.25 to 2.85 eV (referenced to the Si0+ component) with the number of ALD cycles. The oxygen stoichiometric coefficient of the silicate is close to the expected value of 2 for all the samples. However, the hafnia shows an excess of oxygen for some of the samples. View full abstract»

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  • Modeling of inductively coupled plasma Ar/Cl2/N2 plasma discharge: Effect of N2 on the plasma properties

    Page(s): 011301 - 011301-11
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    A global kinetic model of Cl2/Ar/N2 plasma discharge has been developed, which allows calculation of the densities and fluxes of all neutral and charged species considered in the reaction scheme, as well as the electron temperature, as a function of the operating conditions. In this work, the results from the global model are first compared to the calculations given by other models. Our simulation results are focused on the effect of nitrogen adding to the Cl2/Ar plasma mixture, which impacts both neutral and charged species transport phenomena. The N2 percentage is varied to the detriment of Cl2 by keeping the total flow rates of Cl2 and N2 constant. In order to better understand the impact of N2 addition to the Cl2/Ar gas mixture, the authors analyzed the output plasma parameters calculated from the model for different N2 flow rate percentages. Indeed, the simulation results show a decrease in electron density and an increase in electron temperature with increasing percentage of N2. Particular attention is paid to the analysis of electronegativity, Cl2 and N2 dissociation, and positive ion to neutral flux ratio evolution by varying percentage of N2. Such parameters have a direct effect on the etching anisotropy of the materials during the etching process. View full abstract»

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  • Can surface cracks and unipolar arcs explain breakdown and gradient limits?

    Page(s): 011302 - 011302-10
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    The authors argue that the physics of unipolar arcs and surface cracks can help understand rf breakdown and vacuum arc data. They outline a model of the basic mechanisms involved in breakdown and explore how the physics of unipolar arcs and cracks can simplify the picture of breakdown and gradient limits in accelerators, tokamaks as well as laser ablation, micrometeorites, and other applications. Cracks are commonly seen in SEM images of arc damage and they are produced as the liquid metal cools. They can produce the required field enhancements to explain field emission data and can produce mechanical failure of the surface that would trigger breakdown events. Unipolar arcs can produce currents sufficient to short out rf structures, and can cause the sort of damage seen in SEM images. They should be unstable, and possibly self-quenching, as seen in optical fluctuations and surface damage. The authors describe some details and consider the predictions of this simple model. View full abstract»

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  • Reorganization of graphite surfaces into carbon micro- and nanoparticles under high flux hydrogen plasma bombardment

    Page(s): 011303 - 011303-9
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    Fine-grain graphite samples were exposed to high density low temperature (ne∼1020m-3, Te∼1 eV) hydrogen plasmas in the Pilot-PSI linear plasma generator. Redeposition of eroded carbon is so strong that no external precursor gas injection is necessary for deposits to form on the exposed surface during the bombardment. In fact, up to 90% of carbon is redeposited, most noticeably in the region of the highest particle flux. The redeposits appear in the form of carbon microparticles of various sizes and structures. Discharge parameters influence the efficiency of the redeposition processes and the particle growth rate. Under favorable conditions, the growth rate reaches 0.15 μm/s. The authors used high resolution scanning electron microscopy and transmission electron microscopy to study the particle growth mode. The columnar structure of some of the large particles points toward surface growth, while observation of the spherical carbon nanoparticles indicates growth in the plasma phase. Multiple nanoparticles can agglomerate and form bigger particles. The spherical shape of the agglomerates suggests that nanoparticles coalesce in the gas phase. The erosion and redeposition patterns on the samples are likely determined by the gradients in plasma flux density and surface temperature across the surface. View full abstract»

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  • Effects of the gas ambient in thermal activation of Mg-doped p-GaN on Hall effect and photoluminescence

    Page(s): 011502 - 011502-5
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    The effects of thermal annealing in N2, O2, Ar or mixed gas ambient on the electrical and optical properties of metal-organic-chemical-vapor-deposition-grown Mg-doped p-type GaN were investigated by Hall effect and photoluminescence. A systematical study on optimizing annealing gas combination, time, and temperature for achieving high activation efficiency of Mg acceptors was conducted simultaneously. High hole concentration of 9.07 × 1017 cm-3 and low resistivity of 0.622 Ω-cm using the optimized annealing condition were achieved. In agreement with some previous studies, annealing in the mixed gas ambient of N2 and O2 provided significant improvements in activation efficiency of Mg acceptors compared with annealing in pure O2, N2, or Ar. The room- and low-temperature photoluminescence spectra measured from the samples annealed in N2-rich ambient showed significantly higher photoluminescence intensity at both 2.8- and 3.2-eV band transitions. Consistent with the study of others, the experimental results of this study indicated that when annealing in the mixed N2/O2 gas ambient O2 effectively helps activate Mg acceptors by releasing H from Mg-H complexes but also oxidizes GaN; it is likely that the presence of N2 is beneficial in reducing the formation of nitrogen vacancies. View full abstract»

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  • Influence of inert gases on the reactive high power pulsed magnetron sputtering process of carbon-nitride thin films

    Page(s): 011503 - 011503-13
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    The influence of inert gases (Ne, Ar, Kr) on the sputter process of carbon and carbon-nitride (CNx) thin films was studied using reactive high power pulsed magnetron sputtering (HiPIMS). Thin solid films were synthesized in an industrial deposition chamber from a graphite target. The peak target current during HiPIMS processing was found to decrease with increasing inert gas mass. Time averaged and time resolved ion mass spectroscopy showed that the addition of nitrogen, as reactive gas, resulted in less energetic ion species for processes employing Ne, whereas the opposite was noticed when Ar or Kr were employed as inert gas. Processes in nonreactive ambient showed generally lower total ion fluxes for the three different inert gases. As soon as N2 was introduced into the process, the deposition rates for Ne and Ar-containing processes increased significantly. The reactive Kr-process, in contrast, showed slightly lower deposition rates than the nonreactive. The resulting thin films were characterized regarding their bonding and microstructure by x-ray photoelectron spectroscopy and transmission electron microscopy. Reactively deposited CNx thin films in Ar and Kr ambient exhibited an ordering toward a fullerene-like structure, whereas carbon and CNx films deposited in Ne atmosphere were found to be amorphous. This is attributed to an elevated amount of highly energetic particles observed during ion mass spectrometry and indicated by high peak target currents in Ne-containing processes. These results are discussed with respect to the current understanding of the structural evolution of a-C and CNx thin films. View full abstract»

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  • Photoluminescence characterization of polythiophene films incorporated with highly functional molecules such as metallophthalocyanine

    Page(s): 011504 - 011504-11
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    The photoluminescence (PL) of conducting polymer polythiophene (PT) films incorporated with metallophthalocyanines (PcMs) such as CuPc, MgPc, FePc, Li2Pc, and CoPc was studied by PL and time-correlated single photon counting (TCSPC) measurements. Polymer films were prepared by electrochemical polymerization and PcMs migrated into the polymer films by a diffusion method using acetonitrile or toluene as a solvent to dissolve the PcMs. The wavelength of PL emission peaks changed significantly depending on the solvent used in the doping process. Using acetonitrile, the observed PL emission peaks originated from the Q band, whereas they were assigned to the Soret band in the case of toluene. TCSPC measurements showed that PL emission took place through a ligand–ligand transition process when using acetonitrile because the average lifetimes were comparable and independent of the central metal ions for CoPc-, Li2Pc-, and MgPc-doped polymer films. Conversely, using toluene, it was found that ligand–ligand emission occurred for Li2Pc-, MgPc-, and FePc-doped films. To identify the cause of the drastic change in PL emission pattern, x-ray photoelectron spectroscopy measurements were obtained. A lower binding energy component appeared in the C 1s core-level spectra of acetonitrile-processed PcM-doped PT films, whereas this component shifted to higher energy and overlapped with the main peak for toluene-processed PcM-doped PT films. The lower binding energy component corresponded to photoelectrons due to the C atoms in the benzene rings of the ligand. Lower binding energy components also appeared in the N 1s core-level spectra of acetonitrile-processed PcM-doped PT films, and this component shifted to higher energy for toluene-processed PcM-doped PT films. These lower energy components were assigned to the core-level peaks due to the N atoms at the meso position bridging between pyrrole rings. This suggests that the electron char- e at the N sites of the meso positions in toluene-processed films was smaller than in acetonitrile-processed ones. The changes in energy at benzene C sites and meso N sites suggest that the electronic states of the phthalocyanine in the toluene-processed films were porphyrin-like, so the Soret band became dominant in the PL emission spectrum. View full abstract»

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  • Direct comparison of spectroscopic data with cluster calculations of plutonium dioxide and uranium dioxide

    Page(s): 013001 - 013001-3
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    The density of states predicted by cluster calculations of PuO2 and UO2 is directly compared to the results from soft x-ray spectroscopy. Remarkably good agreement between the experimentally measured spectroscopic peaks and the calculated density of states of the central part of the cluster is observed. View full abstract»

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  • Magnetically coupled ultrahigh vacuum manipulator with a sample grabber

    Page(s): 013201 - 013201-4
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    The authors present a simple design for a magnetically coupled manipulator capable of grabbing small samples in an ultrahigh vacuum environment. The opening and closing of the sample grabber is accomplished by the relative rotation of independent rings of magnets. This manipulator provides high values of axial force (30 lb) and azimuthal torque (23 in. lb). View full abstract»

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  • Aluminum-doped zinc oxide formed by atomic layer deposition for use as anodes in organic light emitting diodes

    Page(s): 01A101 - 01A101-6
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    Aluminum-doped zinc oxide films produced by atomic layer deposition were investigated for use as anodes in organic light emitting diode (OLED) devices. Al-doped ZnO (AZO) films (∼200 nm thick) were deposited at temperatures of 200, 230, and 260 °C and the AZO film deposited at 260 °C demonstrated carrier mobility, carrier concentration, resistivity, and transmittance values of 16.2 cm2 V-1 s-1, 5.18 × 1020 cm-3, 7.34 × 10-4 Ω cm, and 90%, respectively. OLED devices with a DNTPD/TAPC/Bebq2:10% doped RP-411/Bphen/LiF/Al structure on a glass substrate fabricated using an AZO anode formed at 260 °C showed turn-on voltage, maximum luminance, and current efficiency values of 5.3 V, 16680 cd/m2, and 4.8 cd/A, respectively. View full abstract»

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  • Atomic layer deposition of Ti-HfO2 dielectrics

    Page(s): 01A102 - 01A102-7
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    Titanium-doped hafnium oxide films, TixHf1-xO2-δ, have been deposited with a Ti content of x = 0.1 and x = 0.5, by atomic layer deposition. The TixHf1-xO2-δ growth rate is lower compared with the growth rates of the individual binary oxides; however, the composition of the films is unaffected by the reduced growth rate. An 850  °C spike anneal and a 500  °C 30 min furnace anneal were performed, and the resulting film composition and structure was determined using medium energy ion scattering, x-ray diffraction, and transmission electron microscopy. The Ti0.1Hf0.9O2-δ films readily crystallize into a monoclinic phase during both types of annealing. By contrast, the Ti0.5Hf0.5O2-δ films remain amorphous during both annealing processes. Electrical characterization of the as-deposited Ti0.1Hf0.9O2-δ films yielded a dielectric constant of 20, which is slightly higher than undoped HfO2 films. The as-deposited Ti0.5Hf0.5O2-δ films showed a significant increase in dielectric constant up to 35. After a 500  °C 30 min anneal, the dielectric constant reduced slightly to 27. The leakage current density of the amorphous film remains relatively unaffected at 8.7×10-7 A/cm2 at -1 MV/cm, suggesting this composition/heat treatment is a candidate for future device dielectrics. View full abstract»

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  • Atomically precise surface engineering of silicon CCDs for enhanced UV quantum efficiency

    Page(s): 01A103 - 01A103-9
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    The authors report here on a new technique, combining the atomic precision of molecular beam epitaxy and atomic layer deposition, to fabricate back illuminated silicon CCD detectors that demonstrate world record detector quantum efficiency (>50%) in the near and far ultraviolet (155–300 nm). This report describes in detail the unique surface engineering approaches used and demonstrates the robustness of detector performance that is obtained by achieving atomic level precision at key steps in the fabrication process. The characterization, materials, and devices produced in this effort will be presented along with comparison to other approaches. View full abstract»

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  • Height distribution of atomic force microscopy images as a tool for atomic layer deposition characterization

    Page(s): 01A104 - 01A104-9
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    The authors propose the analysis of surface height histograms as a tool for the atomic layer deposition (ALD) growth characterization in the initial stage of the process. ALD of HfO2 on a Si(100)/SiO2 substrate was investigated in situ by ultra high vacuum atomic force microscope working in noncontact mode. The ALD cycles, made by using tetrakis-di-methyl-amido-Hf and H2O as precursors, were performed at 230 °C. After each ALD cycle, the relation between the film growth and the root mean square surface roughness was studied. Parameters equivalent to HfO2 layer thickness, coverage, and surface roughness of the substrate and deposited material can be calculated in the proposed routine. View full abstract»

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  • X-ray photoelectron spectroscopy study on the chemistry involved in tin oxide film growth during chemical vapor deposition processes

    Page(s): 01A105 - 01A105-6
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    The chemistry of atmospheric pressure chemical vapor deposition (APCVD) processes is believed to be complex, and detailed reports on reaction mechanisms are scarce. Here, the authors investigated the reaction mechanism of monobutyl tinchloride (MBTC) and water during SnO2 thin film growth using x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). XPS results indicate an acid–base hydrolysis reaction mechanism, which is tested with multilayer experiments, demonstrating self-terminating growth. In-house developed TEM wafers are used to visualize nucleation during these multilayer experiments, and results are compared with TEM results of APCVD samples. Results show almost identical nucleation behavior implying that their growth mechanism is identical. Our experiments suggest that in APCVD, when using MBTC and water, SnO2 film growth occurs via a heterolytic bond splitting of the Sn-Cl bonds without the need to invoke gas-phase radical or coordination chemistry of the MBTC precursor. View full abstract»

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  • Substrate-biasing during plasma-assisted atomic layer deposition to tailor metal-oxide thin film growth

    Page(s): 01A106 - 01A106-9
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    Two substrate-biasing techniques, i.e., substrate-tuned biasing and RF biasing, have been implemented in a remote plasma configuration, enabling control of the ion energy during plasma-assisted atomic layer deposition (ALD). With both techniques, substrate bias voltages up to -200 V have been reached, which allowed for ion energies up to 272 eV. Besides the bias voltage, the ion energy and the ion flux, also the electron temperature, the electron density, and the optical emission of the plasma have been measured. The effects of substrate biasing during plasma-assisted ALD have been investigated for Al2O3, Co3O4, and TiO2 thin films. The growth per cycle, the mass density, and the crystallinity have been investigated, and it was found that these process and material properties can be tailored using substrate biasing. Additionally, the residual stress in substrates coated with Al2O3 films varied with the substrate bias voltage. The results reported in this article demonstrate that substrate biasing is a promising technique to tailor the material properties of thin films synthesized by plasma-assisted ALD. View full abstract»

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  • Ion conduction in nanoscale yttria-stabilized zirconia fabricated by atomic layer deposition with various doping rates

    Page(s): 01A107 - 01A107-4
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    The ion conduction of yttria-stabilized zirconia (YSZ) was studied by varying the doping ratios during atomic layer deposition (ALD). The ALD cycle ratio for the yttria and zirconia depositions was varied from 1:1 to 1:6, which corresponded to the doping ratios from 28.8% to 4.3%. The in-plane conductivity of ALD YSZ was enhanced by up to 2 orders of magnitude; the optimal ALD doping ratio (10.4%) was found to differ from that of bulk YSZ (8%). This different relationship between the doping ratio and the ion conduction for ALD YSZ versus bulk YSZ is due to the inhomogeneous doping in the vertical direction of the ALD YSZ films, as opposed to the homogenous doping of bulk YSZ. View full abstract»

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  • On the kinetics of spatial atomic layer deposition

    Page(s): 01A108 - 01A108-7
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    Spatial atomic layer deposition (ALD) is a promising technology for high deposition rate and high-throughput ALD that can be used for roll-to-roll and large-area applications. In an ideal spatial ALD reactor, the design of the injector should be tuned to the deposition kinetics of the ALD reaction, requiring an in-depth knowledge of the dependencies of the growth per cycle (GPC) on the main kinetic parameters. The authors have investigated the deposition kinetics of spatial ALD of alumina from trimethylaluminum and H2O at atmospheric pressure. A kinetic model was developed, which describes the growth per cycle as a function of the main kinetic parameters. The observation of a √t time dependency in the GPC indicates that precursor diffusion to substrate is rate limiting. Next to a fundamental insight into the kinetics of atmospheric pressure spatial ALD, this model can be used for design optimization of new spatial ALD reactors. Furthermore, the model shows that the maximum alumina deposition rates obtainable with spatial ALD are in the order of several nm/s. View full abstract»

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  • Atomic layer deposition of Al-doped ZnO thin films

    Page(s): 01A109 - 01A109-4
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    Atomic layer deposition has been used to fabricate thin films of aluminum-doped ZnO by depositing interspersed layers of ZnO and Al2O3 on borosilicate glass substrates. The growth characteristics of the films have been investigated through x-ray diffraction, x-ray reflection, and x-ray fluorescence measurements, and the efficacy of the Al doping has been evaluated through optical reflectivity and Seebeck coefficient measurements. The Al doping is found to affect the carrier density of ZnO up to a nominal Al dopant content of 5 at. %. At nominal Al doping levels of 10 at. % and higher, the structure of the films is found to be strongly affected by the Al2O3 phase and no further carrier doping of ZnO is observed. View full abstract»

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  • Low temperature deposition of Ga2O3 thin films using trimethylgallium and oxygen plasma

    Page(s): 01A110 - 01A110-4
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    Gallium oxide (Ga2O3) thin films were deposited by plasma-enhanced atomic layer deposition (ALD) using trimethylgallium as the gallium precursor and oxygen plasma as the oxidant. A wide ALD temperature window was observed from 100 to 400 °C, where deposition rate was constant at ∼0.53 Å/cycle. X-ray photoelectron spectroscopy survey scans indicated the presence of gallium, oxygen, and carbon elements with concentrations of ∼36, ∼51.8, and ∼12.2 at. %, respectively. As-deposited films were amorphous; upon annealing at 900 °C under N2 atmosphere for 30 min, polycrystalline β-Ga2O3 phase with a monoclinic crystal structure was obtained. Refractive index and root mean square roughness of the annealed Ga2O3 film were higher than those of the as-deposited due to crystallization. View full abstract»

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  • Excitation of radiative polaritons by polarized broadband infrared radiation in thin oxide films deposited by atomic layer deposition

    Page(s): 01A111 - 01A111-4
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    This work contributes to the understanding of infrared radiation interaction with matter and its absorption for energy harvesting purposes. By exciting radiative polaritons in thin oxide films with polarized infrared radiation, a further evidence is collected that a link exists between radiative polaritons and the heat recovery mechanism hypothesized in previous research. In the voltage transient occurring when the infrared radiation is turned on, the observed time necessary to reach the maximum voltage and the voltage intensity versus angle of incidence exhibit a mismatch when generated by polarized and nonpolarized infrared radiation. The existence of collective charge oscillation modes in the semiconductor-based elements of the thermoelectric power generators supporting the heat recovery mechanism is suggested as the main source of the discrepancy. View full abstract»

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  • Chemistry of Cu(acac)2 on Ni(110) and Cu(110) surfaces: Implications for atomic layer deposition processes

    Page(s): 01A112 - 01A112-10
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    The thermal chemistry of copper(II)acetylacetonate, Cu(acac)2, on Ni(110) and Cu(110) single-crystal surfaces was probed under vacuum by using x-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). Some data for acetylacetone (Hacac, CH3COCH2COCH3) adsorbed on Ni(110) are also reported as reference. Chemical transformations were identified in several steps covering a temperature range from 150 K to at least 630 K. The desorption of Hacac and a 3-oxobutanal (CH3COCH2CHO) byproduct was observed first at 150 and 180 K on Ni(110) and at 160 and 185 K on Cu(110), respectively. Partial loss of the acetylacetonate (acac) ligands and a likely change in adsorption geometry are seen next, with the possible production of HCu(acac), which desorbs at 200 and 235 K from the nickel and copper surfaces, respectively. Molecular Cu(acac)2 desorption is observed on both surfaces at approximately 300 K, probably from recombination of Cu(acac) and acac surface species. The remaining copper atoms on the surface lose their remaining acac ligands to the substrate and become reduced directly to metallic copper. At the same time, the organic ligands follow a series of subsequent surface reactions, probably involving several C–C bond-scissions, to produce other fragments, additional Hacac and HCu(acac) in the gas phase in the case of the copper surface, and acetone on nickel. A significant amount of acac must nevertheless survive on the surface to high temperatures, because Hacac peaks are seen in the TPD at about 515 and 590 K and the C 1s XPS split associated with acac is seen up to close to 500 K. In terms of atomic layer deposition processes, this suggests that cycles could be design to run at such temperatures as long as an effective hydrogenation agent is used as the second reactant to remove the surface acac a- Hacac. Only a small fraction of carbon is left behind on Ni after heating to 800 K, whereas more carbon and additional oxygen remains on the surface in the case of Cu. View full abstract»

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  • Combining dynamic and static depth profiling in low energy ion scattering

    Page(s): 01A113 - 01A113-3
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    The advantages of combining dynamic and static depth profiling in low energy ion scattering are demonstrated for an Si/SiOx/W/Al2O3 ALD stack. Dynamic depth profiling can be used to calibrate static depth profiling. Energy losses of 152 and 215 eV/nm were found for 3 keV 4He+ and 5 keV 4He+ primary ions, respectively, for the experimental configuration used. This is in good agreement with the values used in the field. Static depth profiling can be used to recognize sputter artifacts in dynamic depth profiles. View full abstract»

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  • Crystal AlN deposited at low temperature by magnetic field enhanced plasma assisted atomic layer deposition

    Page(s): 01A114 - 01A114-7
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    In this paper, AlN films prepared at low temperature by magnetic field enhanced plasma assisted atomic layer deposition (PA-ALD) using trimethyl aluminum and the mixture gas of nitrogen and hydrogen were investigated. Two discharge modes were employed for PA-ALD AlN, i.e., radio-frequency (RF) discharge mode and microwave electron cyclotron resonance (ECR) mode. The structure of the film, compositions, crystallinity, surface roughness, and properties of refractive index as well as photoluminescence were studied by Fourier transform infrared spectroscope, x-ray photoelectron spectroscope, x-ray diffraction, atomic force microscope, spectroscopic ellipsometry, and photoluminescence spectrometer, respectively. Comparison of the as-deposited films prepared in two discharge modes, the authors result that temperature played an important role in in ECR mode, AlN films deposited in ECR mode at 250 °C is crystalline except a little bit of aluminum rich with the contamination of carbon and oxygen; whereas in RF discharge mode, the direct interaction of plasma, the all process parameters affect the properties of the AlN films, like the strength of magnetic field, deposition temperature. The intense emission band measured through photoluminescence spectrum of the as-deposited AlN suggests that there may be potential applications in electronic and optoelectronic nanodevices. View full abstract»

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  • HfxZr1-xO2 compositional control using co-injection atomic layer deposition

    Page(s): 01A115 - 01A115-5
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    As a replacement for SiO2 based gate dielectrics, HfO2 with an admixture of ZrO2 has the potential to provide a higher dielectric constant than pure HfO2 by means of stabilization of higher-k phases. Accordingly, in this study the authors have pursued a means to control composition of HfxZr1-xO2 films grown by atomic layer deposition by simultaneously flowing Hf and Zr metal precursors during the precursor exposure step and varying the molar flow ratio. Using the tetrakis(ethylmethylamino) Hf and Zr precursors, TEMAH and TEMAZ, with either H2O or O3 co-reactants, the co-injection approach for HfxZr1-xO2 was compared with alternating HfO2 and ZrO2 growth cycles and was observed to allow uniform and tunable composition control. For the co-injection process, deviation from the cycle ratio trendline suggests more efficient chemisorption of TEMAZ compared to TEMAH. The authors have also evaluated these films in metal–oxide–semiconductor capacitor structures and verified the electrical equivalence and similar within-wafer distributions of Hf0.2Zr0.8O2 obtained from both processing schemes. View full abstract»

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  • Atomic layer deposition of anatase TiO2 on porous electrodes for dye-sensitized solar cells

    Page(s): 01A116 - 01A116-5
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    Thin TiO2 films were grown by atomic layer deposition on planar and porous substrates and characterized by Raman spectroscopy, x-ray diffraction, high resolution transmission electron microscopy, and spectroscopic ellipsometry. The growth conditions of anatase TiO2 are investigated, motivated by the application in dye-sensitized solar cells, where best results are achieved with electrodes based on anatase TiO2. To enforce an anatase TiO2 growth on substrates stimulating rutile growth, a symmetry breaking ultra thin buffer layer of five cycles Al2O3 was introduced. With this buffer layer anatase TiO2 deposition was demonstrated on planar rutile TiO2 substrates. However, it was found that the necessity of the buffer layer depends on the substrate structure. On porous TiO2 electrodes containing a mixture of anatase and rutile TiO2 domains, a direct anatase TiO2 growth was possible even without a buffer layer. View full abstract»

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Aims & Scope

The Journal of Vacuum Science and Technology A is devoted to reports of original research, review articles, and Critical Review articles.

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G. Lucovsky
North Carolina State University