The influence of adsorbate on the work function and penetrability of the surface potential barrier of GaAs(110) single crystal

2002 ◽  
Vol 36 (11) ◽  
pp. 1283-1287 ◽  
Author(s):  
Yu. I. Asalkhanov ◽  
V. N. Abarykov
Keyword(s):  
Single Crystal ◽  
Work Function ◽  
Potential Barrier ◽  
Surface Potential

scholarly journals Charge Densities above Pulsar Polar Caps

2000 ◽  
Vol 177 ◽  
pp. 463-464
Author(s):  
A. Jessner ◽  
H. Lesch ◽  
Th. Kunzl
Keyword(s):  
Neutron Star ◽  
Electric Field ◽  
Work Function ◽  
Potential Barrier ◽  
Electric Fields ◽  
Surface Potential ◽  
Thermal Emission ◽  
Equilibrium Density ◽  
Charge Densities ◽  
Polar Caps

A simplified model provided the framework for our investigation into the distribution of energy and charge densities above the polar caps of a rotating neutron star. We assumed a neutron star withm= 1.4M⊙,r= 10km, dipolar field |B0| = 1012G,B||Ω and Ω = 2Π · (0.5s)−1. The effects of general relativity were disregarded. The induced accelerating electric fieldE||reachesE0= 2.5 · 1013V m−1at the surface near the magnetic poles. The current density along the field lines has an upper limitnGJ, when the electric field of the charged particle flow cancels the induced electric field: At the polesnGJ(r=rns,θ= 0) = 1.4 · 1017m−3.The work function(surface potential barrier)EWis approximated by the Fermi energyEFof magnetised matter. Following Abrahams and Shapiro (1992) one needs to revise the surface density from the canonical 1.4 · 108kg m−3down toρFe = 2.9 · 107kg m−3. Withwe obtain a value ofEF=Ew= 417eV. There are two relevant particle emission processes:Field (cold cathode) emissionby quantum-mechanical tunneling of charges through the surface potentialandthermal emissionwhich is a purely classical process. In strong electric fields it is enhanced by the lowering of the potential barrier due to the Schottky effect. The combined Dushman-Schottky equationwithtells us, thatat temperatures> 2 · 105K the the Goldreich-Julian current can be supplied thermal emission alone. The surface temperature however has a lower limit in the order of 105K due to the rotational braking. Therefore, in most cases a sufficient supply of charges for the Goldreich-Julian current is available and the electrical field accelerating the particles will be quenched as a result of their abundance. Otherwise a residual equilibrium electric field Eeqremains with:and hence the equilibrium density is:n=nfieid(Eeq,EW) +nDS(Eeq,EW,T) For a temperature just below the onset of thermal emission (T= 1.85 · 105K) the charge density is found to vary almost linearly with the work functionEWfor values ofEWbetween 0.3 and 2 keV. At the chosen value forEWof 417 eVthe residual electric field amounts to only 8.5% of the vacuum value. Even in the residual electric field the particles are rapidly accelerated to relativistic energies balanced by inverse Compton and curvature radiation losses.

scholarly journals Phase Transition Effect on Ferroelectric Domain Surface Charge Dynamics in BaTiO3 Single Crystal

Materials ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4463
Author(s):  
Dongyu He ◽  
Xiujian Tang ◽  
Yuxin Liu ◽  
Jian Liu ◽  
Wenbo Du ◽  
...  
Keyword(s):  
Phase Transition ◽  
Domain Wall ◽  
Single Crystal ◽  
Surface Charge ◽  
Potential Barrier ◽  
Surface Potential ◽  
Topological Defects ◽  
Ferroelectric Domain ◽  
Charge Dynamics ◽  
Surrounding Environment

The ferroelectric domain surface charge dynamics after a cubic-to-tetragonal phase transition on the BaTiO3 single crystal (001) surface was directly measured through scanning probe microscopy. The captured surface potential distribution shows significant changes: the domain structures formed rapidly, but the surface potential on polarized c domain was unstable and reversed its sign after lengthy lapse; the high broad potential barrier burst at the corrugated a-c domain wall and continued to dissipate thereafter. The generation of polarization charges and the migration of surface screening charges in the surrounding environment take the main responsibility in the experiment. Furthermore, the a-c domain wall suffers large topological defects and polarity variation, resulting in domain wall broadening and stress changes. Thus, the a-c domain wall has excess energy and polarization change is inclined to assemble on it. The potential barrier decay with time after exposing to the surrounding environment also gave proof of the surface screening charge migration at surface. Thus, both domain and domain wall characteristics should be taken into account in ferroelectric application.

Epitaxial ferroelectric thin films

1994 ◽  
Vol 52 ◽  
pp. 572-573
Author(s):  
S. G. Ghonge ◽  
E. Goo ◽  
R. Ramesh ◽  
R. Haakenaasen ◽  
D. K. Fork
Keyword(s):  
Single Crystal ◽  
Work Function ◽  
Nonvolatile Memory ◽  
Ferroelectric Properties ◽  
Electrical Contact ◽  
Memory Devices ◽  
Ferroelectric Films ◽  
Si Substrates ◽  
Electro Optic ◽  
Wide Range

Microstructure of epitaxial ferroelectric/conductive oxide heterostructures on LaAIO3(LAO) and Si substrates have been studied by conventional and high resolution transmission electron microscopy. The epitaxial films have a wide range of potential applications in areas such as non-volatile memory devices, electro-optic devices and pyroelectric detectors. For applications such as electro-optic devices the films must be single crystal and for applications such as nonvolatile memory devices and pyroelectric devices single crystal films will enhance the performance of the devices. The ferroelectric films studied are Pb(Zr0.2Ti0.8)O3(PLZT), PbTiO3(PT), BiTiO3(BT) and Pb0.9La0.1(Zr0.2Ti0.8)0.975O3(PLZT).Electrical contact to ferroelectric films is commonly made with metals such as Pt. Metals generally have a large difference in work function compared to the work function of the ferroelectric oxides. This results in a Schottky barrier at the interface and the interfacial space charge is believed to responsible for domain pinning and degradation in the ferroelectric properties resulting in phenomenon such as fatigue.

Evolution of surface potential barrier for negative-electron-affinity GaAs photocathodes

2009 ◽  
Vol 105 (1) ◽  
pp. 013714 ◽  
Author(s):  
Jijun Zou ◽  
Benkang Chang ◽  
Zhi Yang ◽  
Yijun Zhang ◽  
Jianliang Qiao
Keyword(s):  
Potential Barrier ◽  
Surface Potential ◽  
Electron Affinity ◽  
Negative Electron Affinity

FORMATION OF SURFACE DIPOLES FOR SMALL PALLADIUM CLUSTERS DEPOSITED ON α-(0001)Al2O3

1996 ◽  
Vol 03 (01) ◽  
pp. 973-977 ◽  
Author(s):  
S. OGAWA ◽  
S. ICHIKAWA
Keyword(s):  
Charge Transfer ◽  
Single Crystal ◽  
Work Function ◽  
Probe Method ◽  
Kelvin Probe ◽  
Electronic Interactions ◽  
Palladium Clusters ◽  
Metal Support ◽  
Pd Clusters ◽  
Kelvin Probe Method

The Kelvin-probe method is utilized to measure the work function of a single-crystal aluminum covered with palladium clusters. It is found that formation of interface dipoles occurs by charge transfer from Al 2 O 3 to Pd clusters, particularly for those less than 2 nm in diameter. These results provide valuable clue to the understanding of metal-support electronic interactions, which is important in catalysis.

Contactless electroreflectance studies of surface potential barrier for N- and Ga-face epilayers grown by molecular beam epitaxy

2013 ◽  
Vol 103 (5) ◽  
pp. 052107 ◽  
Author(s):  
R. Kudrawiec ◽  
L. Janicki ◽  
M. Gladysiewicz ◽  
J. Misiewicz ◽  
G. Cywinski ◽  
...  
Keyword(s):  
Molecular Beam Epitaxy ◽  
Potential Barrier ◽  
Surface Potential ◽  
Molecular Beam
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