Photoemission Study of The Electronic Structure of Wurtzite Gan(0001) Surfaces

1997 ◽  
Vol 482 ◽  
Author(s):  
Kevin E. Smith ◽  
Sarnjeet S. Dhesi ◽  
Cristian B. Stagarescu ◽  
James Downes ◽  
D. Doppalapudi ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Valence Band ◽  
Surface State ◽  
High Vacuum ◽  
Valence Band Maximum ◽  
Ultra High Vacuum ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Surface Electronic Structure ◽  
Bond State ◽  
Photoemission Study

AbstractThe surface electronic structure of wurtzite GaN (0001) (1 × 1) has been investigated using angle-resolved photoemission spectroscopy. Surfaces were cleaned by repeated cycles of N2 ion bombardment and annealing in ultra-high vacuum. A well-defined surface state below the top of the valence band is clearly observed. This state is sensitive to the adsorption of both activated H2 and O2, and exists in a projected bulk band gap, below the valence band maximum. The state shows no dispersion perpendicular or parallel to the surface. The symmetry of this surface state is even with respect to the mirror planes of the surface and polarization measurements indicate that it is of spz character, consistent with a dangling bond state.

Examination of the Silicon – Silicon Carbide Interface by Ultraviolet Photoemission Spectroscopy

1998 ◽  
Vol 512 ◽  
Author(s):  
C. Koitzscht ◽  
M. O'Brient ◽  
D. Johri ◽  
A. Stoltzt ◽  
R. Nemanicht
Keyword(s):  
Silicon Carbide ◽  
Valence Band ◽  
High Vacuum ◽  
Valence Band Maximum ◽  
Integrated System ◽  
Ultra High Vacuum ◽  
Photoemission Spectroscopy ◽  
Ambient Atmosphere ◽  
Silicon Silicon ◽  
State Feature

ABSTRACTPhotoemission spectroscopy (UPS) was used to investigate the interface properties of deposited silicon on hexagonal 6H-silicon carbide. SiC cleaned in Si flux from a molecular beam epitaxy (MBE) system was used for this study. All processes were accomplished in an ultra high vacuum integrated system that allowed all cleaning, deposition, and analysis to be completed without exposure to ambient atmosphere. Thicknesses of sub- to multiple monolayers were deposited and the valence band structure was investigated. The valence band maximum (VBM) was observed to shift for Si depositions greater than 1 monolayer. The VBM offset was determined to be 2.4eV for a layer of 60Å Si on SiC. Furthermore, the prominent surface state feature of the silicon carbide (0001)si surface is reduced after Si deposition. The results are discussed in terms of the electronic properties of the Si – SiC interface.

Construction Of UHV-REM-PEEM for Surface Studies

1990 ◽  
Vol 48 (1) ◽  
pp. 350-351
Author(s):  
Y. Kondo ◽  
K. Yagi ◽  
K. Kobayashi ◽  
H. Kobayashi ◽  
Y. Yanaka
Keyword(s):  
Electron Microscopy ◽  
Electronic Structure ◽  
High Vacuum ◽  
Scanning Tunneling Spectroscopy ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Surface Electronic Structure ◽  
Electron Microscopes

Recent development of ultra-high vacuum electron microscopy (UHV-EM) is very rapid. This is due to the fact that it can be applied to variety of surface science fields.There are various types of surface imaging in UHV condition; low energy electron microscopy (LEEM) [1], transmission (TEM) and reflection electron microscopy (REM) [2] using conventional transmission electron microscopes (CTEM) (including scanning TEM and REM)), scanning electron microscopy, photoemission electron microscopy (PEEM) [3] and scanning tunneling microscopy (STM including related techniques such as scanning tunneling spectroscopy (STS), atom force microscopy and magnetic force microscopy)[4]. These methods can be classified roughly into two; in one group image contrast is mainly determined by surface atomic structure and in the other it is determined by surface electronic structure. Information obtained by two groups of surface microscopy is complementary with each other. A combination of the two methods may give images of surface crystallography and surface electronic structure. STM-STS[4] and LEEM-PEEM [3] so far developed are typical examples.In the present work a combination of REM(TEM) and PEEM (Fig. 1) was planned with use of a UHV CTEM. Several new designs were made for the new microscope.

scholarly journals Valence band electronic structure of the van der Waals ferromagnetic insulators: VI$$_3$$ and CrI$$_3$$

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Asish K. Kundu ◽  
Yu Liu ◽  
C. Petrovic ◽  
T. Valla
Keyword(s):  
Electronic Structure ◽  
Band Gap ◽  
Valence Band ◽  
Van Der Waals ◽  
Experimental Studies ◽  
Valence Band Maximum ◽  
Atomic Interaction ◽  
Magnetic Ground State ◽  
Half Metallicity ◽  
Angle Resolved Photoemission Spectroscopy

Abstract Ferromagnetic van der Waals (vdW) insulators are of great scientific interest for their promising applications in spintronics. It has been indicated that in the two materials within this class, CrI$$_3$$ 3 and VI$$_3$$ 3 , the magnetic ground state, the band gap, and the Fermi level could be manipulated by varying the layer thickness, strain or doping. To understand how these factors impact the properties, a detailed understanding of the electronic structure would be required. However, the experimental studies of the electronic structure of these materials are still very sparse. Here, we present the detailed electronic structure of CrI$$_3$$ 3 and VI$$_3$$ 3 measured by angle-resolved photoemission spectroscopy (ARPES). Our results show a band-gap of the order of 1 eV, sharply contrasting some theoretical predictions such as Dirac half-metallicity and metallic phases, indicating that the intra-atomic interaction parameter (U) and spin-orbit coupling (SOC) were not properly accounted for in the calculations. We also find significant differences in the electronic properties of these two materials, in spite of similarities in their crystal structure. In CrI$$_3$$ 3 , the valence band maximum is dominated by the I 5p, whereas in VI$$_3$$ 3 it is dominated by the V 3d derived states. Our results represent valuable input for further improvements in the theoretical modeling of these systems.

CHANGES INDUCED IN THE SURFACE ELECTRONIC STRUCTURE OF Be(0001) AFTER Si ADSORPTION

2002 ◽  
Vol 09 (02) ◽  
pp. 687-691
Author(s):  
L. I. JOHANSSON ◽  
C. VIROJANADARA ◽  
T. BALASUBRAMANIAN
Keyword(s):  
Electronic Structure ◽  
Band Structure ◽  
Band Gap ◽  
Electronic Properties ◽  
Surface State ◽  
Core Level ◽  
Clean Surface ◽  
Core Level Spectrum ◽  
Surface Band ◽  
Surface Electronic Structure

A study of effects induced in the Be 1s core level spectrum and in the surface band structure after Si adsorption on Be(0001) is reported. The changes in the Be 1s spectrum are quite dramatic. The number of resolvable surface components and the magnitude of the shifts do decrease and the relative intensities of the shifted components are drastically different compared to the clean surface. The surface band structure is also strongly affected after Si adsorption and annealing. At [Formula: see text] the surface state is found to move down from 2.8 to 4.1 eV. The band also splits at around 0.5 Å-1 along both the [Formula: see text] and [Formula: see text] directions. At [Formula: see text] and beyond [Formula: see text] only one surface state is observed in the band gap instead of the two for the clean surface. Our findings indicate that a fairly small amount of Si in the outer atomic layers strongly modifies the electronic properties of these layers.

scholarly journals Surface electronic structure of theNdB6(110)clean surface studied by angle-resolved photoemission spectroscopy

1997 ◽  
Vol 56 (12) ◽  
pp. 7660-7664 ◽  
Author(s):  
Akinori Tanaka ◽  
Koji Tamura ◽  
Hiroshi Tsunematsu ◽  
Kazutoshi Takahashi ◽  
Masayuki Hatano ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Photoemission Spectroscopy ◽  
Clean Surface ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Surface Electronic Structure

scholarly journals Adsorption geometry, conformation, and electronic structure of 2H-octaethylporphyrin on Ag(111) and Fe metalation in ultra high vacuum

2013 ◽  
Vol 138 (14) ◽  
pp. 144702 ◽  
Author(s):  
Patrizia Borghetti ◽  
Giovanni Di Santo ◽  
Carla Castellarin-Cudia ◽  
Mattia Fanetti ◽  
Luigi Sangaletti ◽  
...  
Keyword(s):  
Electronic Structure ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Adsorption Geometry

scholarly journals (112) Surface of CuInSe2Thin Films with Doped Cd Atoms

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Bo Yin ◽  
Chaogang Lou
Keyword(s):  
Thin Films ◽  
Electronic Structure ◽  
Valence Band ◽  
Electronic Structures ◽  
Formation Energy ◽  
Valence Band Maximum ◽  
Band Maximum ◽  
Doping Behavior

The doping behavior of Cd atoms in the CuInSe2thin films and their influences on electronic structures are investigated. The doped Cd atoms replace Cu atoms and prefer to stay at the (112) surface of the thin films. They combine with Cu vacancies to form defect pairs due to low formation energy. The Cd atom does not by itself modify significantly the electronic structure of the surface, but the defect pairs have important influences. They result in a down shift of valence band maximum and form a hole barrier at the surface, which can prevent holes from reaching the surface and reduce the recombination of carriers.

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