139 research outputs found
Recommended reading list of early publications on atomic layer deposition-Outcome of the "Virtual Project on the History of ALD"
Atomic layer deposition (ALD), a gas-phase thin film deposition technique based on repeated, self-terminating gas-solid reactions, has become the method of choice in semiconductor manufacturing and many other technological areas for depositing thin conformal inorganic material layers for various applications. ALD has been discovered and developed independently, at least twice, under different names: atomic layer epitaxy (ALE) and molecular layering. ALE, dating back to 1974 in Finland, has been commonly known as the origin of ALD, while work done since the 1960s in the Soviet Union under the name "molecular layering" (and sometimes other names) has remained much less known. The virtual project on the history of ALD (VPHA) is a volunteer-based effort with open participation, set up to make the early days of ALD more transparent. In VPHA, started in July 2013, the target is to list, read and comment on all early ALD academic and patent literature up to 1986. VPHA has resulted in two essays and several presentations at international conferences. This paper, based on a poster presentation at the 16th International Conference on Atomic Layer Deposition in Dublin, Ireland, 2016, presents a recommended reading list of early ALD publications, created collectively by the VPHA participants through voting. The list contains 22 publications from Finland, Japan, Soviet Union, United Kingdom, and United States. Up to now, a balanced overview regarding the early history of ALD has been missing; the current list is an attempt to remedy this deficiency. (C) 2016 Author(s).Peer reviewe
ALD Functionalized Nanoporous Gold: Thermal Stability, Mechanical Properties, and Catalytic Activity
Nanoporous metals have many technologically promising applications but their tendency to coarsen limits their long-term stability and excludes high temperature applications. Here, we demonstrate that atomic layer deposition (ALD) can be used to stabilize and functionalize nanoporous metals. Specifically, we studied the effect of nanometer-thick alumina and titania ALD films on thermal stability, mechanical properties, and catalytic activity of nanoporous gold (np-Au). Our results demonstrate that even only one-nm-thick oxide films can stabilize the nanoscale morphology of np-Au up to 1000 C, while simultaneously making the material stronger and stiffer. The catalytic activity of np-Au can be drastically increased by TiO{sub 2} ALD coatings. Our results open the door to high temperature sensor, actuator, and catalysis applications and functionalized electrodes for energy storage and harvesting applications
Reactivities of TaCl5 and H2O as Precursors for Atomic Layer Deposition
Model calculations and time dependence of the deposit mass recorded by quartz crystal microbalance during atomic layer growth of tantalum oxide are used to determine sticking coefficients of TaCl5 and H2O, and diffusion coefficient of TaCl5 in N2. It is shown that the reactivity of TaCl5 towards H2O-treated tantalum oxide surface is remarkably higher than the reactivity of H2O towards TaCl5-treated tantalum oxide
Examining media coverage of the subprime mouurtgage [sic] phenomenon
The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract, appears in the public.pdf file.Title from PDF of title page (University of Missouri--Columbia, viewed on March 19, 2010).Thesis advisor: Dr. Charles Davis.M.A. University of Missouri--Columbia 2009.[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] When both outsiders and insiders attempt to describe bias in the American media, the conversation is primarily dominated by accusations of left-right political partiality. Yet, some scholars contend a more inherent (and potentially more insidious) prejudice is at play; they propose that the media show favoritism toward the American corporate or capitalist class in coverage of economic news. Coverage of the recent subprime mortgage boom (and its subsequent bust) proved a timely laboratory in which to test the premise that economic coverage tilts toward capitalist interests. Specifically, this research was designed to address the hypothesis that stories published before the subprime mortgage collapse would reveal more evidence of a favorable bias toward capitalism than those reported after the crash. Attitudes toward the regulation of markets were treated as the clearest indicator of attitudes toward capitalism; positive judgments about loosely regulated or deregulated markets were considered capitalism-positive while expressions favoring strong regulation were considered capitalism-negative. Two sets of stories were collected, content analyzed and compared: stories published during the subprime mortgage boom (2004-2006) and those published when the mortgage collapse was certain (the last six months of 2008). Intending to measure reports from thought leaders who reach the general American public, The New York Times and CNN were studied. In all, 298 stories were read and coded. After analyzing the samples, the hypothesis was largely proven false. Stories in both samples were generally negative toward capitalism and the regulation of markets.Includes bibliographical reference
Modelling of Precursor Flow and Deposition in Atomic Layer Deposition Reactor
A calculation model to study atomic layer deposition (ALD) in low-pressure channel-type CVD reactor with many parallel substrates is described. The calculations are based on continuity equation and kinetic equation for surface coverage. Formation of a steady-state adsorption wave propagating between the substrates during a precursor pulge is studied. The effect of diffusion and sticking coefficients, carrier gas flow rate and growth temperature on formation and propagation of the steady-state adsorption wave is analysed
Transmission electron microscopy studies of HfO2 thin films grown by chloride-based atomic layer deposition
Detailed transmission electron microscopy characterization of Hf02 films deposited on Si(1 0 0) using atomic layer deposition has been carried out. The influence of deposition temperature has been investigated. At 226 oC, a predominantly quasi-amorphous film containing large grains of cubic Hf02 (a0 = 5.08 Ao) was formed. Grain morphology enabled the nucleation sites to be determined. Hot stage microscopy showed that both the cubic phase and the quasi-amorphous phase were very resistant to thermal modification up to 500 oC. These observations suggest that nucleation sites for the growth of the crystalline cubic phase form at the growing surface of the film, rather homogeneously within the film. The films grown at higher temperatures (300–750 oC) are crystalline and monoclinic. The principal effects of deposition temperature were on: grain size, which coarsens at the highest temperature; roughness with increases at the higher temperatures due to the prismatic faceting, and texture, with texturing being strongest at intermediate temperatures. Detailed interfacial characterization shows that interfacial layers of Si02 form at low and high temperatures. However, at intermediate temperatures, interfaces devoid of Si02 were formed
High-power GaInP-AlGaInP quantum-well lasers grown by solid source molecular beam epitaxy
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