Surface Stoichiometry of CdSe Nanocrystals

1998 ◽  
Vol 536 ◽  
Author(s):  
Jason Taylor ◽  
Tadd Kippeny ◽  
Jonathan C. Bennett ◽  
Mengbing Huang ◽  
Leonard C. Feldman ◽  
...  
Keyword(s):  
High Temperature ◽  
Photoelectron Spectroscopy ◽  
Size Dependence ◽  
Intrinsic Property ◽  
Rutherford Backscattering ◽  
Rutherford Backscattering Spectroscopy ◽  
Trioctylphosphine Oxide ◽  
Cdse Nanocrystals ◽  
X Ray

AbstractRutherford backscattering spectroscopy (RBS) has been applied to determine the constitution of prototypical CdSe nanocrystals synthesized by the high temperature pyrolysis of organometallics in trioctylphosphine oxide (TOPO). The diameter of the nanocrystals was varied from 22 Å to 58 Å. For all nanocrystal sizes the nanocrystals are Cd rich with an average Cd:Se ratio of 1.2 ± 0.1. The Cd:Se stoichiometery is independent of the starting Cd:Se ratio used for nanocrystal preparation, indicating the excess Cd is not associated with the initial abundance but is an intrinsic property of nanocrystals prepared by this method. The size dependence of excess Cd indicates the extra Cd is on the surface of the crystallite. The coverage of the surface passivating TOPO ligands has also been determined and is larger than reported in previous X-ray photoelectron spectroscopy (XPS) studies of Bowen Katari et al. The origin and structural implications of non-stoichoimetric Cd are discussed.

Photo-Chemical Changes of Aluminium Films on Silicon

1988 ◽  
Vol 119 ◽  
Author(s):  
A. J. Kellock ◽  
J. S. Williams ◽  
G. L. Nyberg ◽  
J. Liesegang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Surface Oxidation ◽  
Rutherford Backscattering ◽  
Rutherford Backscattering Spectroscopy ◽  
Chemical Changes ◽  
X Ray ◽  
Surface And Interface ◽  
Photon Irradiation

AbstractX-ray Photoelectron Spectroscopy and Rutherford Backscattering Spectroscopy with channeling are employed to study surface and interface changes resulting from irradiation of thin Al films on Si-SiO2 substrates using < 6eV visible photons. Results indicati that surface oxidation and bonding rearrangements at the Al-SiO2-Si interface can take place at room temperature under photon bombardment. These changes are correlated with enhanced adhesion and modification of film etch properties which are also a result of photon irradiation.

Characterization of Thermally Oxidized SiO2/SiC Interfaces by Leakage Current under High Electric Field, Cathode Luminescence (CL), X-Ray Photoelectron Spectroscopy (XPS) and High-Resolution Rutherford Backscattering Spectroscopy (HR-RBS)

2016 ◽  
Vol 858 ◽  
pp. 449-452
Author(s):  
Yuji Kiuchi ◽  
Hidenori Kitai ◽  
Hiromu Shiomi ◽  
Masatoshi Tsujimura ◽  
Daisuke Nakata ◽  
...  
Keyword(s):  
High Resolution ◽  
Leakage Current ◽  
Photoelectron Spectroscopy ◽  
Rutherford Backscattering ◽  
Rutherford Backscattering Spectroscopy ◽  
Vacancy Defects ◽  
Channel Mobility ◽  
X Ray ◽  
Cathode Luminescence ◽  
Oxide Defects

Wet and N2O oxidized SiO2/SiC for C-face substrates were comprehensively investigated to clarify the origin of oxide defects which affect channel mobility and threshold voltage stability by using leakage-current analysis. The estimated defects are identified by cathode luminescence, X-ray photoelectron spectroscopy, and high-resolution Rutherford backscattering spectroscopy. The origin of the observed oxide defects might be complex defect of O vacancy defects and/or C related defects including N.

Characterizing the Thermomechanical Degradation of a Filled Elastomer by Morphology and X Ray Photoelectron Spectroscopy

2001 ◽  
Vol 702 ◽  
Author(s):  
Giovanni F Crosta ◽  
Art J Nelson ◽  
Marina C Camatini
Keyword(s):  
Photoelectron Spectroscopy ◽  
Intrinsic Property ◽  
Binding Energies ◽  
Structural Domain ◽  
X Ray ◽  
Vulcanized Rubber ◽  
A Value ◽  
Debris Particles ◽  
Morphological Descriptor ◽  
Microscopy Images

ABSTRACTThree types of debris particles, denoted by L2, H2 and K3 respectively, originated from the abrasion of silica-filled, vulcanized rubber under different test conditions (severity) were analyzed and compared. The structural fractal dimension, DFS, of the particle perimeter was chosen as a morphological descriptor (but not necessarily as an intrinsic property of the fractured material !). Said dimension was estimated by processing light microscopy images. A value of the morphological threshold, TST, which separates the textural from the structural domain in the RICHARDSON plot was determined in order to maximize discrimination between the three particle types and rank them by increasing values of DFS. Particles from the highest severity test (K3) exhibited the highest value of DFS. X ray photoelectron spectroscopy (XPS) provided elemental composition, core level binding energies and the speciation of C, N, O, Si and S. As a result, L2 debris was found to originate from two processes: fracture of rubber and segregation of extender oil. Evidence has come both from morphology and XPS. Particles of H2 and K3 were ascribed to fracture alone. Comparison between K3 and the reference material, rasped rubber (RAS), shows the following: a) increase of the [S]/[C] surface atomic concentration ratio from RAS to K3; b) existence of multiple bonding states of S in K3 with energy peaking at 162.9 ± 0.3 eV ([-S-S-]n); c) weak contribution of R-S-O-R oxidized S species in K3 at 165 eV, not seen in RAS; d) no evidence of either SO3 or SO4 groups in any material. Although preliminary, these results prove the ability of morphological analysis and XPS to characterize the surface properties of debris particles non destructively.

Xps Analysis of the Sapphire Surface as a Function of High Temperature Vacuum Annealing

1989 ◽  
Vol 159 ◽  
Author(s):  
E.D. Richmond
Keyword(s):  
High Temperature ◽  
Binding Energy ◽  
Photoelectron Spectroscopy ◽  
Vacuum Annealing ◽  
Xps Analysis ◽  
Chemical Changes ◽  
Cleaning Procedure ◽  
Sapphire Surface ◽  
X Ray ◽  
First Time

ABSTRACTFor the first time the (1102) surface of sapphire has been investigated by X-ray photoelectron spectroscopy to ascertain chemical changes resulting from annealing in vacuum at 1300° C and 1450° C. As received substrates had a substantial surface C contaminant. For substrates that were chemically cleaned before inserting them into the MBE system no trace of carbon is detected. A residual flourine contaminant results from the cleaning procedure and is desorbed by the vacuum annealing. Spectra of annealed substrates are compared to the unannealed chemically cleaned substrates. The annealed substrates exhibit 0.4 to 0.5 eV shift to higher binding energy of the Al peak and a 0.3 eV shift to higher binding energy of the O peak. In addition, a 2% depletion of oxygen from the surface occurs.

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