A new method to detect energy‐band bending using x‐ray photoemission spectroscopy

1988 ◽  
Vol 64 (2) ◽  
pp. 753-757 ◽  
Author(s):  
T. Ogama
Keyword(s):  
Energy Band ◽  
New Method ◽  
Photoemission Spectroscopy ◽  
Band Bending ◽  
X Ray ◽  
Energy Band Bending

scholarly journals Limits on mass outflow from optical tidal disruption events

2021 ◽  
Vol 502 (3) ◽  
pp. 3385-3393
Author(s):  
Tatsuya Matsumoto ◽  
Tsvi Piran
Keyword(s):  
Energy Band ◽  
New Method ◽  
Hydrodynamic Modelling ◽  
X Rays ◽  
Will Emit ◽  
Tidal Disruption ◽  
X Ray ◽  
Mass Outflow ◽  
Current Sample ◽  
Stellar Masses

ABSTRACT The discovery of optical/UV (ultraviolet) tidal disruption events (TDEs) was surprising. The expectation was that, upon returning to the pericentre, the stellar-debris stream will form a compact disc that will emit soft X-rays. Indeed, the first TDEs were discovered in this energy band. A common explanation for the optical/UV events is that surrounding optically thick matter reprocesses the disc’s X-ray emission and emits it from a large photosphere. If accretion follows the super-Eddington mass infall rate, it would inevitably result in an energetic outflow, providing naturally the reprocessing matter. We describe here a new method to estimate, using the observed luminosity and temperature, the mass and energy of outflows from optical transients. When applying this method to a sample of supernovae, our estimates are consistent with a more detailed hydrodynamic modelling. For the current sample of a few dozen optical TDEs, the observed luminosity and temperature imply outflows that are significantly more massive than typical stellar masses, posing a problem to this common reprocessing picture.

Photoemission Studies of the Ag/InP(110) Interface: Interfacial Reactions and Schottky Barrier Formation

1983 ◽  
Vol 25 ◽  
Author(s):  
W. G. Petro ◽  
T. Kendelewicz ◽  
I. A. Babalola ◽  
I. Lindau ◽  
W. E. Spicer
Keyword(s):  
Valence Band Maximum ◽  
Interfacial Reactions ◽  
Core Level ◽  
Photoemission Spectroscopy ◽  
Band Bending ◽  
X Ray ◽  
Barrier Formation ◽  
Deconvolution Technique ◽  
P Type ◽  
Measurable Change

ABSTRACTRoom-temperature interfacial reactions at the Ag/InP (110) interface have been studied using soft x-ray photoemission spectroscopy of the In 4d and P 2p core levels. For low Ag coverages (less than 1 monolayer (ML)) no measurable change in core level shapes is observed, and the shift in core level position is due solely to band bending. At high Ag coverages (up to 72 ML) we observe dissociated In metal, P atoms near the surface, and Ag clustering. Fermi level movement is deduced from these spectra using a deconvolution technique, and pinning positions of 0.40 ± 0.05 eV below the conduction-band minimum for n-type and 0.5 ± 0.l eV above the valence-band maximum for p-type are found. These positions are in close agreement with calculations of native defect levels.

New Electronic Properties of Metal / III-V Compound Semiconductor Interfaces

1989 ◽  
Vol 148 ◽  
Author(s):  
L. J. Brillson ◽  
R. E. Viturro ◽  
S. Chang ◽  
J. L. Shaw ◽  
C. Mailhiot ◽  
...  
Keyword(s):  
Compound Semiconductor ◽  
Photoemission Spectroscopy ◽  
Dominant Effect ◽  
Band Bending ◽  
X Ray ◽  
Barrier Heights ◽  
Semiconductor Interfaces ◽  
Cathodoluminescence Spectroscopy ◽  
Wide Range ◽  
Spectroscopy Studies

ABSTRACTRecent studies of interface states and band bending at metal / III-V compound semiconductor interfaces reveal that these junctions are much more controllable and predictable than commonly believed. Soft x-ray photoemission spectroscopy studies demonstrate a wide range of band bending for metals on many III-V compounds, including GaAs. Cathodoluminescence spectroscopy measurements show that discrete states form at the microscopic junction which can have a dominant effect on the band bending properties. Internal photoemission measurements confirm the bulk barrier heights inferred by photoemission methods. After separating out surface chemical and bulk crystal quality effects, one finds simple, predictive barrier height variations which follow classical Schottky behavior.

Band Bending at the Gold (Au)/Boron Carbide-Based Semiconductor Interface

2018 ◽  
Vol 232 (5-6) ◽  
pp. 893-905 ◽  
Author(s):  
Elena Echeverría ◽  
George Peterson ◽  
Bin Dong ◽  
Simeon Gilbert ◽  
Adeola Oyelade ◽  
...  
Keyword(s):  
Boron Carbide ◽  
Aromatic Compounds ◽  
Chemical Vapor ◽  
Binding Energies ◽  
Photoemission Spectroscopy ◽  
Semiconductor Interface ◽  
Band Bending ◽  
X Ray ◽  
Barrier Formation ◽  
P Type

Abstract We have used X-ray photoemission spectroscopy to study the interaction of gold (Au) with novel boron carbide-based semiconductors grown by plasma-enhanced chemical vapor deposition (PECVD). Both n- and p-type films have been investigated and the PECVD boron carbides are compared to those containing aromatic compounds. In the case of the p-type semiconducting PECVD hydrogenated boron carbide samples, the binding energy of the B(1s) core level shows a shift to higher binding energies as the Au is deposited, an indication of band bending and possibly Schottky barrier formation. In the case of the n-type boron carbide semiconductors the interaction at the interface is more typical of an ohmic contact. Addition of the aromatic compounds increases the change in binding energies on both n-type and p-type PECVD boron carbide semiconductors, and the gold appears to diffuse into the PECVD boron carbides alloyed with aromatic moieties.

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