Valence band discontinuity at the GaN/SiC(0 0 0 1) heterojunction studied in situ by synchrotron-radiation photoelectron spectroscopy

2005 ◽  
Vol 144-147 ◽  
pp. 425-428 ◽  
Author(s):  
C.-H. Chen ◽  
L. Aballe ◽  
R. Klauser ◽  
T.U. Kampen ◽  
K. Horn
1985 ◽  
Vol 49 ◽  
Author(s):  
F. Evangelisti ◽  
S. Modesti ◽  
F. Boscherini ◽  
P. Fiorini ◽  
C. Quaresima ◽  
...  

AbstractThe heterostructures obtained by growing a-Ge on a-Si:H and a-Si have been investigated by synchrotron radiation photoemission. We measured valence band and core level spectra on the heterostructures grown in situ under ultrahigh-vacuum conditions. A step-by-step monitoring of possible band-bending changes during the interface formation enabled us to determine unambiguously the band discontinuities. The measured values of the valence band discontinuity were 0.2 ± 0.1 eV for a-Si:H/a-Ge and 0.0 ± 0.1 eV for a-Si/a-Ge, respectively. Evidence was found for the formation of abrupt interfaces without interdiffusion.


1995 ◽  
Vol 378 ◽  
Author(s):  
Art J. Nelson ◽  
K. Sinha ◽  
John Moreland

AbstractSynchrotron radiation soft x-ray photoemission spectroscopy was used to investigate the development of the electronic structure at the CdS/Cu2Se heterojunction interface. Cu2−xSe layers were deposited on GaAs (100) by molecular beam epitaxy from Cu2Se sources. Raman spectra reveal a strong peak at 270 cm−1, indicative of the Cu2−xSe phase. Atomic force microscopy reveals uniaxial growth in a preferred (100) orientation. CdS overlayers were then deposited in-situ, at room temperature, in steps on these epilayers. Photoemission measurements were acquired after each growth in order to observe changes in the valence band electronic structure as well as changes in the Se3d and Cd4d core lines. The results were used to correlate the interfacial chemistry with the electronic structure and to directly determine the CdS/Cu2−xSe and heterojunction valence band discontinuity and the consequent heterojunction band diagram. These results are compared to the valence band offset (ΔEv) for the CdS/CuInSe2 heterojunction interface.


1995 ◽  
Vol 377 ◽  
Author(s):  
M. Sebastiani ◽  
L. Di Gaspare ◽  
C. Bittencourt ◽  
F. Evangelisti

ABSTRACTWe report the first yield spectroscopy study on well characterized c-Si/a-Si:H heterojunctions grown in situ under UHV conditions. We find that this spectroscopy, when operated in the constant final state mode, allows a direct and precise determination of the valence-band discontinuity at the interface. A value of δEv = 0.44 ± 0.02 eV was found for the discontinuity.


2001 ◽  
Vol 114-116 ◽  
pp. 1191-1196 ◽  
Author(s):  
N. Franco ◽  
J.E. Klepeis ◽  
C. Bostedt ◽  
T. Van Buuren ◽  
C. Heske ◽  
...  

2005 ◽  
Vol 16 (8) ◽  
pp. 1326-1334 ◽  
Author(s):  
V N Strocov ◽  
G E Cirlin ◽  
J Sadowski ◽  
J Kanski ◽  
R Claessen

1994 ◽  
Vol 349 ◽  
Author(s):  
S. Gonda ◽  
M. Kawasaki ◽  
T. Arakane ◽  
H. Koinuma

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.


Nanomaterials ◽  
2022 ◽  
Vol 12 (2) ◽  
pp. 231
Author(s):  
Galina I. Semushkina ◽  
Yuliya V. Fedoseeva ◽  
Anna A. Makarova ◽  
Dmitry A. Smirnov ◽  
Igor P. Asanov ◽  
...  

Fluorinated graphitic layers with good mechanical and chemical stability, polar C–F bonds, and tunable bandgap are attractive for a variety of applications. In this work, we investigated the photolysis of fluorinated graphites with interlayer embedded acetonitrile, which is the simplest representative of the acetonitrile-containing photosensitizing family. The samples were continuously illuminated in situ with high-brightness non-monochromatized synchrotron radiation. Changes in the compositions of the samples were monitored using X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The NEXAFS N K-edge spectra showed that acetonitrile dissociates to form HCN and N2 molecules after exposure to the white beam for 2 s, and the latter molecules completely disappear after exposure for 200 s. The original composition of fluorinated matrices CF0.3 and CF0.5 is changed to CF0.10 and GF0.17, respectively. The highly fluorinated layers lose fluorine atoms together with carbon neighbors, creating atomic vacancies. The edges of vacancies are terminated with the nitrogen atoms and form pyridinic and pyrrolic units. Our in situ studies show that the photolysis products of acetonitrile depend on the photon irradiation duration and composition of the initial CFx matrix. The obtained results evaluate the radiation damage of the acetonitrile-intercalated fluorinated graphites and the opportunities to synthesize nitrogen-doped graphene materials.


2019 ◽  
Vol 61 (12) ◽  
pp. 2294
Author(s):  
С.Н. Тимошнев ◽  
А.М. Мизеров ◽  
Г.В. Бенеманская ◽  
С.А. Кукушкин ◽  
А.Д. Буравлев

The results of experimental studies of the electronic and photoemission properties of an epitaxial GaN layer grown on a SiC/Si(111) substrate by plasma assisted molecular beam epitaxy are presented. The electronic structure of the GaN surface and ultrathin Li/GaN interface was first studied in situ under ultrahigh vacuum conditions under different Li coverages. The experiments were performed using photoelectron spectroscopy with synchrotron radiation in the photon energy range of 75–850 eV. The photoemission spectra in the region of the valence band and surface states and the photoemission spectra from the N 1s, Ga 3d, Li 2s core levels were studied for different submonolayer Li coverages. It is established that Li adsorption causes significant changes in the general form of the spectra induced by charge transfer between the Li layer and the lower N and Ga layers. It is established that the GaN surface has predominantly N-polarity. The semiconductor character of the Li / GaN interface is shown.


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