Electronic Properties of Wide Bandgap Materials

1997 ◽  
Vol 483 ◽  
Author(s):  
J.E. Yater ◽  
A. Shih ◽  
R. Abrams
Keyword(s):  
Energy Distribution ◽  
Electron Distribution ◽  
Secondary Electron ◽  
Impact Ionization ◽  
Incident Beam ◽  
Wide Bandgap ◽  
Low Energy ◽  
Internal Gain ◽  
Low Energy Electrons ◽  
The Impact

AbstractSecondary electron emission spectroscopy is used to investigate the generation and transport of impact-ionized electrons in wide bandgap material. Secondary electron yield and energy distribution measurements from C(100) and CVD diamond samples are analyzed to obtain information about the internal gain and electron energy distribution following impact ionization, as well as the effects of the transport process on the internal electron distribution. By studying the emission from surfaces having a negative electron affinity (NEA), the total transmitted intensity and the full energy spectrum of the internal electrons are revealed in the measurements. Energy spectra measured from the diamond samples contain a low-energy peak whose energy position and width are independent of incident beam energy. This suggests that the peak represents the electron distribution produced by impact-ionization events. A large percentage of the total emitted electrons lie within this peak, indicating that the impact-ionization process is very efficient at generating low-energy electrons. Very high yields are measured from both samples, establishing the presence of high internal gain and efficient electron transport in the material. From the linear slope of the yield curves, the escape depth of the low-energy electrons is deduced to be much larger than ˜ 0.1 μm in both diamond samples.

Secondary Electron Emission Studies of Diamond and GaN Materials

1999 ◽  
Vol 558 ◽  
Author(s):  
J.E. Yater ◽  
A. Shih ◽  
D.S. Katzer
Keyword(s):  
Electron Emission ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Cvd Diamond ◽  
Secondary Emission ◽  
Low Energy ◽  
Energy Distributions ◽  
Three Samples ◽  
Low Energy Electrons ◽  
The Impact

ABSTRACTSecondary electron emission spectroscopy is used to examine the transport and emission of low-energy electrons in several wide bandgap materials. In particular, the secondary emission properties of C(100), C(111), and CVD diamond samples are compared in order to examine the effect of crystallographic orientation on the emission characteristics. Very high yields are obtained from hydrogenated and cesiated negative-electron-affinity surfaces of all three samples, indicating that low-energy electrons are transported and emitted very efficiently in the diamond materials. While the energy distribution of the emitted electrons is found to be sharply peaked at low energy for all three samples, the energy distributions measured from the C(111) surfaces are broader and reveal structure in the energy gap. The different emission processes at the C(100) and C(111) surfaces may account for the energy distributions observed from the polycrystalline CVD diamond. Finally, initial secondary emission measurements are taken from GaN and AlGaN films grown by molecular beam epitaxy. The secondary emission is not as strong as from the diamond samples, and the measurements reveal the impact of interface and surface barriers on the emission process.

Low Energy Electron Impact Ionization and Fragmentation: Cyclobutanone

1973 ◽  
Vol 51 (4) ◽  
pp. 624-627 ◽  
Author(s):  
Graham Richard Branton ◽  
Claudio Kong Nam Pua
Keyword(s):  
Energy Distribution ◽  
Electron Impact ◽  
Mass Spectrometer ◽  
Ionization Energy ◽  
Impact Ionization ◽  
Electron Impact Ionization ◽  
Low Energy ◽  
Energy Electron ◽  
Low Energy Electron

Cyclobutanone is shown to yield both C3H6+ and C2H2O+ ions on fragmentation under electron impact in a mass spectrometer. Using the energy distribution difference (EDD) technique the ionization energy of cyclobutanone is found to be 9.58 eV and the appearance potentials of the C3H6+ and C2H2O+ ions are found to be 9.85 and 10.53 eV, respectively.

POSSIBLE "HOT" MOLECULE DESORPTION BY ELECTRON STIMULATED DECOMPOSITION OF DIHALOETHANES ON Cu(111)

1994 ◽  
Vol 01 (04) ◽  
pp. 535-538 ◽  
Author(s):  
S. TURTON ◽  
M. KADODWALA ◽  
ROBERT G. JONES
Keyword(s):  
Electron Capture ◽  
Photoelectron Spectroscopy ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Negative Ions ◽  
Low Energy ◽  
First Order ◽  
Sufficient Energy ◽  
Low Energy Electrons ◽  
Low Energy Electron

The desorption of ethene from physisorbed 1, 2-dichloroethane (DCE) and 1-bromo-2-chloroethane (BCE) on Cu(111) has been observed on irradiating the surface with electrons. The techniques used were low energy electron diffraction (LEED), Auger electron spectroscopy (AES), ultraviolet photoelectron spectroscopy (UPS), and mass spectrometric detection of the desorbed species. At 110 K physisorbed DCE and BCE underwent electron capture from low energy (<1 eV ) electrons in the secondary electron yield of the surface followed by decomposition and desorption of ethene alone. The decomposition was found to be first order in the surface coverage of the physisorbed DCE/BCE. No other molecular species desorbed from the surface, a stoichiometric amount of chemisorbed halogen was deposited and no carbon was detectable at the end of the desorption. The formation of the negative ions of these molecules by electron capture of low energy electrons in the secondary electron emission from the surface and the possible dynamics by which the negative ions undergo decomposition leaving the ethene product with sufficient energy to desorb, are discussed.

Pseudopotential calculations of elastic scattering of low-energy electrons (< 20 eV) from neon atoms

1992 ◽  
Vol 70 (5) ◽  
pp. 305-310 ◽  
Author(s):  
Y. Frongillo ◽  
B. Plenkiewicz ◽  
P. Plenkiewicz ◽  
J.-P. Jay-Gerin
Keyword(s):  
Elastic Scattering ◽  
Energy Range ◽  
Cross Sections ◽  
Impact Energy ◽  
Theoretical Data ◽  
Low Energy ◽  
Pseudopotential Calculations ◽  
Low Energy Electrons ◽  
The Impact ◽  
Good Agreement

Pseudopotential calculations of phase shifts, differential, total, and momentum-transfer cross sections for electrons elastically scattered from neon atoms are reported in the impact energy range 0–20 eV. The results are found to be in very good agreement with existing experimental and other theoretical data.

Can we use graphene as a conversion surface for a neutral particle detector?

2020 ◽  
Author(s):  
Alexander Grigoriev ◽  
Andrei Fedorov ◽  
Nicolas André
Keyword(s):  
Secondary Electron ◽  
Grazing Angle ◽  
Secondary Electron Emission ◽  
Incident Beam ◽  
Particle Energy ◽  
Low Energy ◽  
Wafer Surface ◽  
Neutral Atoms ◽  
Energetic Neutral Atoms ◽  
First Case

&lt;p&gt;An important technique of modern space plasma diagnostics is a detection and imaging of low energy (below 10 keV) energetic neutral atoms (ENA). Any space mission devoted to study of the planetary plasma environments, planetary magnetospheres and heliosphere boundaries, needs a low energy ENA imaging sensor in its payload list. A common approach to the ENA detection/imaging is to make energetic neutral atoms glance a high quality conductive surface and either produce a secondary electron, or produce a positive or negative reflection ion. In the first case we can collect and detect the yielded secondary electron and generate a start signal. The reflected neutral atom can be directed to another surface with a high secondary electron yield. Thus we can measure a time-of-flight of the reflected particle to get its velocity. In the second case we can analyze the reflected ion in an electrostatic analyzer to get the particle energy.&lt;/p&gt;&lt;p&gt;Many types of conversion surfaces have been investigated over last decades in order to optimize an ENA sensor properties. We investigated properties of a thin layer of graphene applied to a silicon wafer surface. The experimental setup consisted of a secondary electron detector, neutral/ions separator and a high resolution particle imager. We used an incident He beam with energy of 200 eV - 3000 eV. We obtained a secondary electron emission, particle reflection efficiency, scattering properties, and a positive ion production rate as a function of the incident beam energy and the grazing angle. The experiment results show that 1) Graphene is a good source of secondary electrons even for low energy incident particles; 2) ENA scatter from the graphene surface similar to other surface types; 3) Graphene does not convert incident ENA to positive ions, especially for high grazing angles.&lt;/p&gt;

Decay of secondary electron emission and charging of hydrogenated and hydrogen-free diamond film surfaces induced by low energy electrons

2002 ◽  
Vol 91 (7) ◽  
pp. 4726-4732 ◽  
Author(s):  
A. Hoffman ◽  
A. Laikhtman ◽  
S. Ustaze ◽  
M. Hadj Hamou ◽  
M. N. Hedhili ◽  
...  
Keyword(s):  
Electron Emission ◽  
Diamond Film ◽  
Secondary Electron ◽  
Secondary Electron Emission ◽  
Low Energy ◽  
Low Energy Electrons
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