scholarly journals Collective amplification of nearby nanoparticles in the Coulomb blockade restricted charging of a single nanoparticle

2021 ◽  
Author(s):  
Baptiste Chatelain ◽  
Ali El Barraj ◽  
Clémence Badie ◽  
Lionel Santinacci ◽  
Clemens Barth
Keyword(s):  
Coulomb Blockade ◽  
High Vacuum ◽  
Atomic Layer ◽  
Ultra High Vacuum ◽  
Kelvin Probe ◽  
Charge Detection ◽  
Research Fields ◽  
Supported Metal Nanoparticles ◽  
General Desire ◽  
Interest In Research

Abstract The characterization of charges in oxide supported metal nanoparticles (NP) is of high interest in research fields like heterogeneous catalysis and microelectronics. A general desire is to manipulate the charge of an oxide supported single NP and to characterize afterwards the charge and its interference with the insulating support but also with nearby NPs in the vicinity. By using noncontact AFM (nc-AFM) and Kelvin probe force microscopy (KPFM) in ultra-high vacuum (UHV) and at room temperature we show that a ~5 nm small AuNP can be directly charged with electrons by the AFM tip and that upon the charging, nearby AuNPs sensitively change their electrostatic potential with a large impact on the charge detection by nc-AFM and KPFM. The AuNPs are supported on a 40 nm thick insulating Al2O3 film, which is grown by atomic layer deposition (ALD) on Si(001). Due to Coulomb blockades, the NP charging appears in the form of large and discrete peaks in detuning versus bias voltage curves. Finite element method (FEM) calculations reveal that the large peaks can only be observed when the potentials of nearby insulated NPs get modified by the NP's electron charge, according to the electrostatic induction principle. In view of the number of transferred electrons, we anticipate that after the charging, the electrons are transferred from the AuNP to the NP-Al2O3 interface or into Al2O3 subsurface regions directly underneath.

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>

Laser cleaning of exfoliated graphene

2012 ◽  
Vol 1455 ◽  
Author(s):  
Oliver Ochedowski ◽  
Benedict Kleine Bußmann ◽  
Marika Schleberger
Keyword(s):  
Local Heating ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Ambient Conditions ◽  
Kelvin Probe ◽  
Structural Modifications ◽  
Force Microscopy ◽  
Exfoliated Graphene ◽  
Atomic Force ◽  
P Type

ABSTRACTWe have employed atomic force and Kelvin-Probe force microscopy to study graphene sheets exfoliated on TiO2 under the influence of local heating achieved by laser irradiation. Exfoliation and irradiation took place under ambient conditions, the measurements were performed in ultra high vacuum. We show that after irradiation times of 6 min, an increase of the surface potential is observed which indicates a decrease of p-type carrier concentration. We attribute this effect to the removal of adsorbates like water and oxygen. After irradiation times of 12 min our topography images reveal severe structural modifications of graphene. These resemble the nanocrystallite network which form on graphene/SiO2 but after much longer irradiation times. From our results we propose that short laser heating at moderate powers might offer a way to clean graphene without inducing unwanted structural modifications.

Work function study of rhenium oxidation using an ultra high vacuum scanning Kelvin probe

2000 ◽  
Vol 88 (7) ◽  
pp. 4371 ◽  
Author(s):  
I. D. Baikie ◽  
U. Petermann ◽  
A. Speakman ◽  
B. Lägel ◽  
K. M. Dirscherl ◽  
...  
Keyword(s):  
Work Function ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Kelvin Probe ◽  
Function Study ◽  
Scanning Kelvin Probe

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.

Characterization of Oxides and Thin Films

1993 ◽  
Vol 309 ◽  
Author(s):  
Iain D. Baikie ◽  
Gerrit H. Bruggink
Keyword(s):  
Work Function ◽  
Local Density ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Interface Condition ◽  
Semiconductor Surface ◽  
Kelvin Probe ◽  
Preparation Methods ◽  
Surface And Interface ◽  
Wide Range

AbstractUsing a new, high resolution, microscopic Scanning Kelvin Probe (SKP), work function topographies of metal, semiconductor and metal/semionductor surfaces have been studied in both Ultra-High-Vacuum (UHV) and air environments.The work function is a very sensitive indicator of surface and Interface condition and has been previously utilized to examine preparation methods, surface roughness, adsorption processes, thin film monitoring and residual surface contamination.Extension of the basic method, via Illumination of the semiconductor surface under the tip allows one to probe the local density of states (LDOS). Variations in LDOS can be used to monitor metal contamination, interface traps, bulk contamination, oxide imperfections, etc.Work function topographies generated in this fashion have application in quality control at all stages of the manufacturing process. The Kelvin method of measuring work function is non-contact and non-destructive, utilizing neither high fields nor large currents. It can be applied to a variety of environments ranging from UHV to air and at a wide range of temperatures.

scholarly journals Precise control of atoms with MBE: from semiconductors to complex oxides

2020 ◽  
Vol 51 (4) ◽  
pp. 21-23
Author(s):  
Y. Eren Suyolcu ◽  
Gennady Logvenov
Keyword(s):  
Molecular Beam ◽  
High Vacuum ◽  
Complex Oxides ◽  
Atomic Layer ◽  
Atomic Clusters ◽  
Ultra High Vacuum ◽  
Mbe Growth ◽  
Precise Control ◽  
Material Systems ◽  
Layer Control

Molecular Beam Epitaxy (MBE) is a high-vacuum technique with atomic-layer control and precision. It is based on the chemical reaction of the atoms, molecules, or atomic clusters vaporized from the specific evaporation sources on the substrates. The molecular beam defines a unidirectional ballistic flow of atoms and/or molecules without any collisions amongst. In the late 1960s, MBE was initially developed for the growth of GaAs and (Al, Ga)As systems[1,2] due to the unprecedented capabilities and then was applied to study other material systems. MBE growth is conventionally performed in vacuum and ultra-high vacuum (UHV) (10-8–10-12 mbar) conditions.

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