Coverage and Stability of NHx Terminated Cobalt and Ruthenium Surfaces: a First Principles Investigation

2019 ◽  
Author(s):  
Ji Liu ◽  
Michael Nolan
Keyword(s):  
Metal Surfaces ◽  
High Vacuum ◽  
Atomic Layer ◽  
Nitrogen Plasma ◽  
Operating Conditions ◽  
Ultra High Vacuum ◽  
Bridge Site ◽  
Stable Surface ◽  
Saturation Coverage ◽  
The Stability

<div>In the atomic layer deposition (ALD) of Cobalt (Co) and Ruthenium (Ru) metal using nitrogen plasma, the structure and composition of the post N-plasma NHx terminated (x = 1 or 2) metal surfaces are not well known but are important in the subsequent metal containing pulse. In this paper, we use the low-index (001) and (100) surfaces of Co and Ru as models of the metal polycrystalline thin films. The (001) surface with a hexagonal surface structure is the most stable surface and the (100) surface with a zigzag structure is the least stable surface but has high reactivity. We investigate the stability of NH and NH2 terminations on these surfaces to determine the saturation coverage of NHx on Co and Ru. NH is most stable in the hollow hcp site on (001) surface and the bridge site on the (100) surface, while NH2 prefers the bridge site on both (001) and (100) surfaces. The differential energy is calculated to find the saturation coverage of NH and NH2. We also present results on mixed NH/NH2-terminations. The results are analyzed by thermodynamics using Gibbs free energies (ΔG) to reveal temperature effects on the stability of NH and NH2 terminations. Ultra-high vacuum (UHV) and standard ALD</div><div>operating conditions are considered. Under typical ALD operating conditions we find that the most stable NHx terminated metal surfaces are 1 ML NH on Ru (001) surface (350K-550K), 5/9 ML NH on Co (001) surface (400K-650K) and a mixture of NH and NH2 on both Ru (100) and Co (100) surfaces.</div>

scholarly journals Coverage and Stability of NHx Terminated Cobalt and Ruthenium Surfaces: a First Principles Investigation

2019 ◽  
Author(s):  
Ji Liu ◽  
Michael Nolan
Keyword(s):  
Metal Surfaces ◽  
High Vacuum ◽  
Atomic Layer ◽  
Nitrogen Plasma ◽  
Operating Conditions ◽  
Ultra High Vacuum ◽  
Bridge Site ◽  
Stable Surface ◽  
Saturation Coverage ◽  
The Stability

<div>In the atomic layer deposition (ALD) of Cobalt (Co) and Ruthenium (Ru) metal using nitrogen plasma, the structure and composition of the post N-plasma NHx terminated (x = 1 or 2) metal surfaces are not well known but are important in the subsequent metal containing pulse. In this paper, we use the low-index (001) and (100) surfaces of Co and Ru as models of the metal polycrystalline thin films. The (001) surface with a hexagonal surface structure is the most stable surface and the (100) surface with a zigzag structure is the least stable surface but has high reactivity. We investigate the stability of NH and NH2 terminations on these surfaces to determine the saturation coverage of NHx on Co and Ru. NH is most stable in the hollow hcp site on (001) surface and the bridge site on the (100) surface, while NH2 prefers the bridge site on both (001) and (100) surfaces. The differential energy is calculated to find the saturation coverage of NH and NH2. We also present results on mixed NH/NH2-terminations. The results are analyzed by thermodynamics using Gibbs free energies (ΔG) to reveal temperature effects on the stability of NH and NH2 terminations. Ultra-high vacuum (UHV) and standard ALD</div><div>operating conditions are considered. Under typical ALD operating conditions we find that the most stable NHx terminated metal surfaces are 1 ML NH on Ru (001) surface (350K-550K), 5/9 ML NH on Co (001) surface (400K-650K) and a mixture of NH and NH2 on both Ru (100) and Co (100) surfaces.</div>

scholarly journals Precise nanoscale temperature mapping in operational microelectronic devices by use of a phase change material

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Qilong Cheng ◽  
Sukumar Rajauria ◽  
Erhard Schreck ◽  
Robert Smith ◽  
Na Wang ◽  
...  
Keyword(s):  
Thin Film ◽  
Phase Change ◽  
Phase Change Material ◽  
Heat Dissipation ◽  
Radiation Thermometry ◽  
High Vacuum ◽  
Operating Conditions ◽  
Ultra High Vacuum ◽  
Scanning Thermal Microscopy ◽  
Change Material

AbstractThe microelectronics industry is pushing the fundamental limit on the physical size of individual elements to produce faster and more powerful integrated chips. These chips have nanoscale features that dissipate power resulting in nanoscale hotspots leading to device failures. To understand the reliability impact of the hotspots, the device needs to be tested under the actual operating conditions. Therefore, the development of high-resolution thermometry techniques is required to understand the heat dissipation processes during the device operation. Recently, several thermometry techniques have been proposed, such as radiation thermometry, thermocouple based contact thermometry, scanning thermal microscopy, scanning transmission electron microscopy and transition based threshold thermometers. However, most of these techniques have limitations including the need for extensive calibration, perturbation of the actual device temperature, low throughput, and the use of ultra-high vacuum. Here, we present a facile technique, which uses a thin film contact thermometer based on the phase change material $$Ge_2 Sb_2 Te_5$$ G e 2 S b 2 T e 5 , to precisely map thermal contours from the nanoscale to the microscale. $$Ge_2 Sb_2 Te_5$$ G e 2 S b 2 T e 5 undergoes a crystalline transition at $$\hbox {T}_{{g}}$$ T g with large changes in its electric conductivity, optical reflectivity and density. Using this approach, we map the surface temperature of a nanowire and an embedded micro-heater on the same chip where the scales of the temperature contours differ by three orders of magnitude. The spatial resolution can be as high as 20 nanometers thanks to the continuous nature of the thin film.

Eine Methode zur Messung geringster Ölbedeckungen in Vakuumsystemen

1967 ◽  
Vol 22 (4) ◽  
pp. 549-553 ◽  
Author(s):  
R. Dobrozemsky ◽  
W. K. Huber ◽  
F. Viehböck
Keyword(s):  
High Vacuum ◽  
High Sensitivity ◽  
Radioactive Tracer ◽  
Operating Conditions ◽  
Ultra High Vacuum ◽  
Vacuum System ◽  
First Results ◽  
Tracer Isotope ◽  
Radioactive Tracer Method ◽  
Vacuum Systems

To get information on extremely small organic deposits in ultra high vacuum systems the sensitivity of most of the conventional methods for thickness measurements is not high enough. On the other hand the radioactive tracer method has shown its high sensitivity and wide versatility in many fields. Tritium with a half life of 12.3 γ and a mean β-energy of 5.4 keV was choosen as tracer isotope. A method is described for Tritium-labelling diffusion pump oils with specific activities up to 100 mC/g. Using the liquid scintillation counting technique one can detect deposits down to below 1010 molecules/cm2. First results with this Tritium labelled pump fluid are given under different operating conditions in an all metal ultra high vacuum system.

scholarly journals Selective Growth of Al2O3 on Size-Selected Platinum Clusters by Atomic Layer Deposition

2019 ◽  
Author(s):  
Timothy J. Gorey ◽  
Yang Dai ◽  
Scott Anderson ◽  
Sungsik Lee ◽  
Sungwon Lee ◽  
...  
Keyword(s):  
Atomic Layer Deposition ◽  
Photoelectron Spectroscopy ◽  
High Vacuum ◽  
Atomic Layer ◽  
Ultra High Vacuum ◽  
Ex Situ ◽  
Dimensional Structure ◽  
Alumina Layer ◽  
X Ray ◽  
Layer Deposition

In heterogeneous catalysis, atomic layer deposition (ALD) has been developed as a tool to stabilize and reduce carbon deposition on supported nanoparticles. Here, we discuss use of high vacuum ALD to deposit alumina films on size-selected, sub-nanometer Pt/SiO2 model catalysts. Mass-selected Pt24 clusters were deposited on oxidized Si(100), to form model Pt24/SiO2 catalysts with particles shown to be just under 1 nm, with multilayer three dimensional structure. Alternating exposures to trimethylaluminum and water vapor in an ultra-high vacuum chamber were used to grow alumina on the samples without exposing them to air. The samples were probed in situ using X-ray photoelectron spectroscopy (XPS), low-energy ion scattering spectroscopy (ISS), and CO temperature-programmed desorption (TPD). Additional samples were prepared for ex situ experiments using grazing incidence small angle x-ray scattering spectroscopy (GISAXS). Alumina growth is found to initiate at least 60 times more efficiently at the Pt24 cluster sites, compared to bare SiO2/Si, with a single ALD cycle depositing a full alumina layer on top of the clusters, with substantial additional alumina growth initiating on SiO2 sites surrounding the clusters. As a result, the clusters were completely passivated, with no exposed Pt binding sites.

scholarly journals TiO x /Pt3Ti(111) surface-directed formation of electronically responsive supramolecular assemblies of tungsten oxide clusters

2021 ◽  
Vol 12 ◽  
pp. 203-212
Author(s):  
Marco Moors ◽  
Yun An ◽  
Agnieszka Kuc ◽  
Kirill Yu Monakhov
Keyword(s):  
Elevated Temperatures ◽  
High Vacuum ◽  
Operating Conditions ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Unit Cells ◽  
Oxide Phases ◽  
Molecular Nanostructures ◽  
Titanium Oxide Films

Highly ordered titanium oxide films grown on a Pt3Ti(111) alloy surface were utilized for the controlled immobilization and tip-induced electric field-triggered electronic manipulation of nanoscopic W3O9 clusters. Depending on the operating conditions, two different stable oxide phases, z’-TiO x and w’-TiO x , were produced. These phases show a strong effect on the adsorption characteristics and reactivity of W3O9 clusters, which are formed as a result of thermal evaporation of WO3 powder on the complex TiO x /Pt3Ti(111) surfaces under ultra-high vacuum conditions. The physisorbed tritungsten nano-oxides were found as isolated single units located on the metallic attraction points or as supramolecular self-assemblies with a W3O9-capped hexagonal scaffold of W3O9 units. By applying scanning tunneling microscopy to the W3O9–(W3O9)6 structures, individual units underwent a tip-induced reduction to W3O8. At elevated temperatures, agglomeration and growth of large WO3 islands, which thickness is strongly limited to a maximum of two unit cells, were observed. The findings boost progress toward template-directed nucleation, growth, networking, and charge state manipulation of functional molecular nanostructures on surfaces using operando techniques.

scholarly journals Review of 2H-tetraphenylporphyrins metalation in ultra-high vacuum on metal surfaces

2013 ◽  
Vol 470 ◽  
pp. 012012 ◽  
Author(s):  
M Panighel ◽  
G Di Santo ◽  
M Caputo ◽  
C Lal ◽  
B Taleatu ◽  
...  
Keyword(s):  
Metal Surfaces ◽  
High Vacuum ◽  
Ultra High Vacuum
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