Highly Sensitive Analysis for Valence Band Edge of C60 Films by Total Yield Photoelectron Spectroscopy

1994 ◽  
Vol 349 ◽  
Author(s):  
S. Gonda ◽  
M. Kawasaki ◽  
T. Arakane ◽  
H. Koinuma
Keyword(s):  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Total Yield ◽  
Kelvin Probe ◽  
Highly Sensitive ◽  
Gap States ◽  
Kelvin Probe Method ◽  
C60 Films ◽  
Simple Picture

ABSTRACTWe have in-situ measured the density of states (DOS) around the top of valence band of pristine C60 films by means of total yield photoelectron spectroscopy. The top of valence band (TVB) of C60 was located at 5.00eV below the vacuum level. Considerable amplitude of gap states was observed up to 0.9eV above the TVB. Kelvin probe method revealed that the Fermi level of amorphous C60 film was located at 0.47eV above the TVB. The improvement of crystallinity in C60 films, which induced the increase in electrical conductivity as well, increased the DOS above the TVB. The electric conduction of C60 films cannot be explained with a simple picture for carrier conduction in semiconductors.

Effects of Potassium Chemisorption on the Electronic Structure of VxOy/TiO2 Surfaces

1996 ◽  
Vol 454 ◽  
Author(s):  
Fulvio Parmigiani ◽  
Laura E. Depero ◽  
Luigi Sangaletti
Keyword(s):  
Electronic Structure ◽  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Open Shell ◽  
Band Edge ◽  
X Ray ◽  
Core Line ◽  
Band Spectra ◽  
Gap States ◽  
Vanadium Ions

ABSTRACTX-ray photoelectron spectroscopy of pure and K chemisorbed VxOy/TiO2 powders are reported. Core-line and valence band spectra suggest the presence of vanadium open shell ions on the pure VxOy/TiO2 interface, whereas potassium vanadate seems to form after K chemisorption. That results in the presence of a significant amount of gap states, with vanadium character, just above the O2p band edge, for the pure VxOy/TiO2 powder, while K chemisorption, reducing significantly the open shell vanadium ions, quenches the gap emission in the XPS valence band spectra.

Band Tails and Thermal Disorder in Doped and Undoped Hydrogenated Amorphous Silicon and Silicon-Germanium Alloys

1990 ◽  
Vol 192 ◽  
Author(s):  
Samer Aljishi ◽  
J. David Cohen ◽  
Shu Jin ◽  
Lothar Ley
Keyword(s):  
Valence Band ◽  
Conduction Band ◽  
Photoelectron Spectroscopy ◽  
Silicon Germanium ◽  
Total Yield ◽  
Structural Disorder ◽  
Band Tail ◽  
Characteristic Energy ◽  
Densities Of States ◽  
Thermal Disorder

ABSTRACTThe energy distribution and temperature dependence of the conduction and valence band tail density of states in a-Si:H and a-Si,Ge:H alloys is determined via total yield photoelectron spectroscopy. All films are observed to possess purely exponential conduction and valence band tail densities of states; however, the characteristic energy of the conduction band tail increases much more rapidly with temperature in the range of 300K to 550K than that of the valence band tail. This indicates that over that temperature range the conduction band tail is considerably more susceptible to thermal disorder than to structural disorder whereas the reverse holds for the valence band tail.

scholarly journals Электронная структура наноинтерфейса Cs/n-GaN(0001)

2018 ◽  
Vol 44 (6) ◽  
pp. 50
Author(s):  
Г.В. Бенеманская ◽  
М.Н. Лапушкин ◽  
Д.Е. Марченко ◽  
С.Н. Тимошнев
Keyword(s):  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Surface States ◽  
Valence Band Maximum ◽  
Surface Electron ◽  
Electron States ◽  
Band Maximum ◽  
Metallic Character ◽  
First Time

AbstractElectronic structures of the n -GaN(0001) surface and Cs/ n -GaN(0001) interface with submonolayer Cs coverages were studied for the first time in situ by the photoelectron spectroscopy (PES) method. The spectra of photoemission from the valence band, surface electron states, and core levels (Ga 3 d , Cs 4 d , Cs 5 p ) under synchrotron excitation were measured in a range of photon energies within 50–150 eV. Evolution of the spectrum of surface states near the valence-band maximum was revealed by PES during the adsorption of Cs atoms. A metallic character of the Cs/ n -GaN(0001) nano-interface is demonstrated.

scholarly journals Влияние адсорбции атомов натрия и прогрева на наночастицы золота, адсорбированные на вольфраме

2020 ◽  
Vol 62 (8) ◽  
pp. 1171
Author(s):  
П.А. Дементьев ◽  
Е.В. Иванова ◽  
М.Н. Лапушкин ◽  
Д.А. Cмирнов ◽  
С.Н. Тимошнев
Keyword(s):  
Gold Nanoparticles ◽  
Electronic Structure ◽  
Energy Range ◽  
Surface Topography ◽  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Sodium Atoms ◽  
Before And After ◽  
Tungsten Surface

The electronic structure of gold nanoparticles deposited on the surface of tungsten before and after the adsorption of sodium atoms followed by heating at T = 630 K was studied in situ in ultrahigh vacuum by photoelectron spectroscopy. The photoemission spectra from the valence band and core levels of Au 4f and Na 2p were studied under synchrotron excitation in the photon energy range 80-600 eV. It was shown that changes in the spectra of the valence band and core levels of Au 4f and Na 2p are associated with a change in the surface topography caused by the adsorption of sodium atoms and heating, which led to an increase in the surface area by several times. The surface topography and cathodoluminescence of a layer of gold nanoparticles deposited on a tungsten surface are studied

Thermal Equilibration Between Band Tail and Near Surface Defect States in Hydrogenated Amorphous Silicon and Silicon-Germanium Alloys

1990 ◽  
Vol 192 ◽  
Author(s):  
Samer Aljishi ◽  
Shu Jin ◽  
Lothar Ley ◽  
Sigurd Wagner
Keyword(s):  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Silicon Germanium ◽  
Total Yield ◽  
State Density ◽  
Defect States ◽  
Band Tail ◽  
Characteristic Energy ◽  
Near Surface ◽  
Average Value

ABSTRACTWe employ total yield photoelectron spectroscopy to measure the density of occupied states at the clean a-SixGe1_x:H alloy surface. The near surface defect states are observed to lie at 0.57 eV above the valence band edge with a density of 4×l017 cm−3, independent of Ge content. The valence band tail characteristic energy is also measured to be independent of alloy composition with an average value of 54 meV. We demonstrate that thermodynamic equilibrium at the surface between weak bonds (forming the valence band tail) and the dangling bonds provides an excellent description of the experimental data and explains why the surface state density in a-Si:H cannot be lowered below the 1011 to 1012 cm−2 range.

IN-SITU PHOTOELECTRON SPECTROSCOPY OF MAGNETIC DOTS AND MAGNETIC SEMICONDUCTOR NANOSTRUCTURES

2002 ◽  
Vol 16 (11n12) ◽  
pp. 1681-1690 ◽  
Author(s):  
M. OSHIMA ◽  
K. ONO ◽  
M. MIZUGUCHI ◽  
M. YAMADA ◽  
J. OKABAYASHI ◽  
...  
Keyword(s):  
Thin Films ◽  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Magnetic Semiconductor ◽  
Magnetic Nanostructures ◽  
Metallic Behavior ◽  
Fermi Edge ◽  
Magnetic Dots ◽  
Nias Type

High resolution angle-resolved photoelectron spectroscopy (ARPES) has been performed on magnetic nanostructures which were in-situ grown hetero-epitaxially on GaAs substrates by low temperature molecular beam epitaxy. Sulfur termination of GaAs surfaces enabled the formation of NiAs-type MnSb dots and zinc-blende (zb) type MnAs dots, showing huge magnetoresistance at RT and half-metallic behavior, respectively. ARPES analysis revealed that the zb-MnAs dots show unique valence band feature with Mn 3d-related peak at about 4 eV of binding energy which is quite similar to (Ga,Mn)As DMS films. Zb-CrAs thin films on GaAs with T c higher than RT are found to show the band dispersion within 2 eV near the Fermi edge, which is in good agreement with the FLAPW calculation. We have also found that (Ga,Cr)As DMS thin films have the similar valence band features to zb-CrAs

In-Situ XPS Study of the Aluminum Poly(p-Phenylenevinylene) Interface

1995 ◽  
Vol 385 ◽  
Author(s):  
K. Konstadinidis ◽  
F. Papadimitrakopoulos ◽  
M. Galvin ◽  
R. Opila
Keyword(s):  
Valence Band ◽  
Oxygen Content ◽  
Photoelectron Spectroscopy ◽  
Surface Oxygen ◽  
Band Bending ◽  
X Ray ◽  
In Situ Xps ◽  
Synthetic Routes ◽  
Xps Study

ABSTRACTThe chemical and electronic properties of aluminum/poly(p-phenylenevinylene) (PPV) interfaces were studied in situ using x-ray photoelectron spectroscopy (XPS). It was observed that the aluminum atoms react with the oxygen-containing groups present as impurities on the surface of PPV to form Al-O-C linkages. The Al atoms also interact with the wrsystem of the polymer as indicated by changes in the valence band. Contrary to to recent suggestions (Ettedgui et al.) the relation between surface oxygen content and band bending is not straightforward, as shown by deposition on PPV surfaces prepared by two different synthetic routes.

scholarly journals Электронная структура молибдена, окисленного на воздухе

2019 ◽  
Vol 61 (11) ◽  
pp. 2024
Author(s):  
П.А. Дементьев ◽  
Е.В. Иванова ◽  
М.Н. Лапушкин ◽  
Д.А. Смирнов ◽  
С.Н. Тимошнев
Keyword(s):  
Electronic Structure ◽  
Energy Range ◽  
Surface Topography ◽  
Valence Band ◽  
Photoelectron Spectroscopy ◽  
Hydroxyl Group ◽  
Hydrogen Atoms ◽  
The Core ◽  
Spectroscopy Studies

In situ photoelectron spectroscopy studies in ultrahigh vacuum of the electronic structure of the surface of molybdenum oxidized in air and during the adsorption of sodium Na with submonolayer coatings were carried out. The spectra of photoemission from the valence band and the core levels O 1s, O 2s, Mo 4s and Na 2p were studied under synchrotron excitation in the photon energy range of 80 – 600 eV. The change in the spectrum of the oxygen core levels associated with the substitution of hydrogen atoms in the hydroxyl group by sodium atoms was found. The surface topography and cathodoluminescence of molybdenum oxide were studied.

Energy Level Alignment at Tpd/Etal Interfaces Studied by Kelvin Method

1999 ◽  
Vol 558 ◽  
Author(s):  
N. Hayashi ◽  
E. Ito ◽  
H. Ishii ◽  
Y. Ouchi ◽  
K. Seki
Keyword(s):  
Photoelectron Spectroscopy ◽  
Metal Substrate ◽  
Ultraviolet Photoelectron Spectroscopy ◽  
Level Shift ◽  
Organic Metal ◽  
Metal Interface ◽  
Kelvin Probe ◽  
Vacuum Level ◽  
Initial Stage ◽  
Kelvin Probe Method

ABSTRACTThe vacuum level shift A was determined by Kelvin probe method for TPD/metal systems prepared in ultrahigh vacuum (TPD: N, N'-bis(3-methylphenyl)-N, N'-diphenyl-[1, 1'-biphenyl]-4,4'-diamine). The energy of the vacuum level sharply changed at the initial stage of depositing TPD on the metal substrates, and further bending was not observed up to 100 nm thickness of TPD. This result is consistent with our previous studies of ultraviolet photoelectron spectroscopy. These results indicate the invalidity of traditional model with a common vacuum level at organic/metal interface. We discussed the dependence of the vacuum level shift on the work function Φm of the metal substrate (Au, Cu, Ag, Mg, and Ca). A liner correlation between Δ and Φm was observed only in the region of 3.8 eV < Φm < 4.5 eV, indicating that Fermi level alignment is not achieved at least for some interfaces. We found that Δ for TPD film on the air-exposed metal substrate is smaller than that of TPD on clean metals and was observed a liner relation between Φm and Δ except for the Cu substrate.

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