THE KINK EFFECTS IN NANO-GaAs DEVICES DUE TO MULTI-VALLEY ELECTRON TRANSPORT

2013 ◽  
Vol 27 (27) ◽  
pp. 1350172
Author(s):  
LING-FENG MAO ◽  
A. M. JI ◽  
C. Y. ZHU ◽  
Z. O. WANG ◽  
L. J. ZHANG ◽  
...  
Keyword(s):  
Electron Transport ◽  
Carrier Density ◽  
Ballistic Transport ◽  
Drain Current ◽  
Energy Difference ◽  
High Energy ◽  
Channel Length ◽  
Drain Voltage ◽  
High Energy Electrons ◽  
Gaas Devices

The threshold source-drain voltage for the kink occurring in 130 nm GaAs devices is found to be linear dependent on the temperature in experiments. And the source-drain current after kink is also observed to be linearly dependent on the reciprocal of the source-drain voltage. A physical model of source-drain current including multi-valley transport for arbitrary doping and uniform doping GaAs has been proposed to explain such experimental phenomenon. Multi-valley electron transport origins from electrons getting the energy higher than the energy difference between the valleys from the channel electric field due to channel length shorter than the free-length for nano- GaAs devices. High energy electrons due to ballistic transport leads to a redistribution channel electron in different valleys and high energy electrons have a larger probability to occupy the states in upper valley because the density of states of the upper valley is about 70 times larger than that of the lower valley, leads to the carrier density in L valley being comparable with that in Γ valley in the channel, lastly kinks occurs.

scholarly journals Directional transport of fast electrons at the front target surface irradiated by intense femtosecond laser pulses with preformed plasma

2012 ◽  
Vol 30 (1) ◽  
pp. 39-43 ◽  
Author(s):  
X.X. Lin ◽  
Y.T. Li ◽  
B.C. Liu ◽  
F. Liu ◽  
F. Du ◽  
...  
Keyword(s):  
Electron Transport ◽  
Incidence Angle ◽  
Target Surface ◽  
Laser Pulses ◽  
High Energy ◽  
Femtosecond Laser Pulses ◽  
Fast Electrons ◽  
High Energy Electrons ◽  
Preformed Plasma ◽  
Directional Transport

AbstractThe effects of laser incidence angle on lateral fast electron transport at front target surface, when a plasma is preformed, irradiated by intense (>1018 W/cm2) laser pulses, are studied by Kα imaging technique and electron spectrometer. A horizontally asymmetric Kα halo, resulting from directional lateral electron transport and energy deposition, is observed for a large incidence angle (70°). Moreover, a group of MeV high energy electrons is emitted along target surface. It is believed that the deformed preplasma and the asymmetrical distribution of self-generated magnetic field, at large incidence angle, play an important role in the directional lateral electron transport.

scholarly journals Strained SI/SIGE/SI Nano-Channel Hoi Mosfet

2019 ◽  
Vol 8 (2S3) ◽  
pp. 1227-1230
Keyword(s):  
Threshold Voltage ◽  
Silicon Germanium ◽  
Ballistic Transport ◽  
Drain Current ◽  
Channel Length ◽  
Strained Silicon ◽  
Short Channel ◽  
Strained Si ◽  
Dual Channel ◽  
Nano Channel

Strained Si technology has headed in the development of single or dual channel strained silicon MOSFETs devices. Comprehending the need of advancement in recent technologies with miniaturized features, developing a novel MOSFET on ultrathin double strained Si with strained SiGe sandwiched in between and forming a tri-channel MOSFET has been the crux of this present research. Incorporation of quantum carrier confinement effect on the ultrathin dual strained Si layers in the channel has been implemented to counterbalance the threshold voltage roll-off induced by the strained layers. A comparison of the conventional strained silicon on relaxed silicon-germanium with double strained silicon channel MOSFET has been perceived leading to eloquent drain current enhancement of ~49% with a small reduction in the threshold voltage caused by the additional bottom strained Si layer. Further, 100nm and 50nm channel length have been compared and a superior device characteristic for the reduced device dimension is attained as the prominence of velocity overshoot is more in short channel device approaching to quasi-ballistic transport in the channel region

COMPARISON OF SiC AND ZnO FIELD EFFECT TRANSISTORS FOR HIGH POWER APPLICATIONS

2009 ◽  
Vol 23 (20n21) ◽  
pp. 2533-2540 ◽  
Author(s):  
H. ARABSHAHI
Keyword(s):  
Field Effect ◽  
Field Effect Transistors ◽  
Bulk Material ◽  
Ballistic Transport ◽  
Drain Current ◽  
Drain Voltage ◽  
Response Characteristics ◽  
Ensemble Monte Carlo ◽  
Electron Transport Properties ◽  
Frequency Response Characteristics

An ensemble Monte Carlo method is used to compare the potentialities of SiC and ZnO materials for field effect transistors. First, bulk material electron transport properties are compared and then the operation of MESFETs made from them are investigated. The simulated device geometries and doping are matched to the nominal parameters described for the experimental structures as closely as possible. Simulations of SiC MESFETs of lengths 2, 2.6 and 3.2 μm have been carried out and compared these results with those on ZnO MESFETs of the same dimensions. The direct current IV characteristics of the two materials were found to be similar, though the ZnO characteristics were on the whole superior, reaching their operating point at higher drain voltages and possessing higher gains. However, oscillations in the drain current caused by changes in drain voltage in the ZnO devices were not present to the same degree in the SiC devices. This difference is caused partially by the onset of the negative differential regime in SiC at a higher electric field than in ZnO but the primary cause is the longer ballistic transport times in SiC . This suggests that ZnO MESFETs may prove to have superior frequency response characteristics than SiC MESFETs.

Physics and Modelling of Tri-Layered Strained Channel for Development of Double Gate n-channel FET

2021 ◽  
Author(s):  
Kuleen Kumar ◽  
Rudra Sankar Dhar
Keyword(s):  
Ballistic Transport ◽  
Drain Current ◽  
Narrow Channel ◽  
Channel Length ◽  
Charge Carriers ◽  
Double Gate ◽  
Major Objective ◽  
Maximum Charge ◽  
Microelectronic Technology ◽  
Intervalley Scattering

Abstract The strain silicon technology with FET is a dominant technology providing enrichment in carrier velocity in nanoscaled device by change of band structure arrangement. Leakage reduction while enhancement in drain current is another major objective therefore, designing a nano-regime double gate FET with strained channel is perceived. So, design and implementation of a double gate strained heterostructure on insulator (DG-SHOI) FET with tri-layered channel (s-Si/s-SiGe/s-Si) is the core. Biaxial strain is created in channel by inculcating three layers with optimal thicknesses while narrow channel depletion regions are strongly controlled by equipotential gates. Consequently, maximum charge carriers accumulate in channel due to quantum carrier confinement instigating ballistic transport across the 22 nm channel length device leading to lessening of intervalley scattering. In comparison to existing 22 nm DGSOI FET, drain current augmentation of 56% and transconductance amplification of 87.6% is observed while DIBL is prudently reduced for this newly designed and implemented DG-SHOI FET, signifying advancement in microelectronic technology.

scholarly journals O2 and Other High-Energy Molecules in Photosynthesis: Why Plants Need Two Photosystems

Life ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1191
Author(s):  
Klaus Schmidt-Rohr
Keyword(s):  
Energy Transfer ◽  
Electron Transport ◽  
Electron Affinity ◽  
Charge Separation ◽  
Explanatory Power ◽  
High Energy ◽  
Chemical Energy ◽  
Free Energies ◽  
High Energy Electrons ◽  
Hydrogen Donors

The energetics of photosynthesis in plants have been re-analyzed in a framework that represents the relatively high energy of O2 correctly. Starting with the photon energy exciting P680 and “loosening an electron”, the energy transfer and electron transport are represented in a comprehensive, self-explanatory sequence of redox energy transfer and release diagrams. The resulting expanded Z-scheme explicitly shows charge separation as well as important high-energy species such as O2, TyrZ˙, and P680+˙, whose energies are not apparent in the classical Z-scheme of photosynthesis. Crucially, the energetics of the three important forms of P680 and of P700 are clarified. The relative free energies of oxidized and reduced species are shown explicitly in kJ/mol, not encrypted in volts. Of the chemical energy produced in photosynthesis, more is stored in O2 than in glucose. The expanded Z-scheme introduced here provides explanatory power lacking in the classical scheme. It shows that P680* is energetically boosted to P680+˙ by the favorable electron affinity of pheophytin and that Photosystem I (PSI) has insufficient energy to split H2O and produce O2 because P700* is too easily ionized. It also avoids the Z-scheme’s bewildering implication, according to the “electron waterfall” concept, that H2O gives off electrons that spontaneously flow to chlorophyll while releasing energy. The new analysis explains convincingly why plants need two different photosystems in tandem: (i) PSII mostly extracts hydrogen from H2O, producing PQH2 (plastoquinol), and generates the energetically expensive product O2; this step provides little energy directly to the plant; (ii) PSI produces chemical energy for the organism, by pumping protons against a concentration gradient and producing less reluctant hydrogen donors. It also documents that electron transport and energy transfer occur in opposite directions and do not involve redox voltages. The analysis makes it clear that the high-energy species in photosynthesis are unstable, electron-deficient species such as P680+˙ and TyrZ˙, not putative high-energy electrons.

scholarly journals Strain-Dependence of Electron Transport in Bulk Si and Deep-Submicron MOSFETs

VLSI Design ◽  
2001 ◽  
Vol 13 (1-4) ◽  
pp. 163-167 ◽  
Author(s):  
F. M. Bufler ◽  
P. D. Yoder ◽  
W. Fichtner
Keyword(s):  
Electron Transport ◽  
Drain Current ◽  
Channel Length ◽  
Deep Submicron ◽  
Strain Dependence ◽  
Saturation Velocity ◽  
Low Field ◽  
Field Mobility ◽  
Maximum Improvement ◽  
Low Field Mobility

The strain-dependence of electron transport in bulk Si and deep-submicron MOSFETs is investigated by full-band Monte Carlo simulation. On the bulk level, the drift velocity at medium field strengths is still enhanced above Ge-contents of 20% in the substrate, where the low-field mobility is already saturated, while the saturation velocity remains unchanged under strain. In an n-MOSFET with a metallurgical channel length of 50nm, the saturation drain current is enhanced by up to 11%, but this maximum improvement is essentially already achieved at a Ge-content of 20% emphasizing the role of the low-field mobility as a key indicator of device performance in the deep-submicron regime.

scholarly journals Properties of Elementary Particle Fluxes in Primary Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the International Space Station

2019 ◽  
Vol 209 ◽  
pp. 01007
Author(s):  
Francesco Nozzoli
Keyword(s):  
Electron Flux ◽  
Space Station ◽  
Cosmic Ray ◽  
High Energy ◽  
Precision Measurements ◽  
High Energy Electrons ◽  
Electrons And Positrons ◽  
Positron Flux ◽  
Rigidity Dependence ◽  
Alpha Magnetic Spectrometer

Precision measurements by AMS of the fluxes of cosmic ray positrons, electrons, antiprotons, protons as well as their rations reveal several unexpected and intriguing features. The presented measurements extend the energy range of the previous observations with much increased precision. The new results show that the behavior of positron flux at around 300 GeV is consistent with a new source that produce equal amount of high energy electrons and positrons. In addition, in the absolute rigidity range 60–500 GV, the antiproton, proton, and positron fluxes are found to have nearly identical rigidity dependence and the electron flux exhibits different rigidity dependence.

scholarly journals Polar Middle Atmospheric Responses to Medium Energy Electron (MEE) Precipitation Using Numerical Model Simulations

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 133
Author(s):  
Ji-Hee Lee ◽  
Geonhwa Jee ◽  
Young-Sil Kwak ◽  
Heejin Hwang ◽  
Annika Seppälä ◽  
...  
Keyword(s):  
Climate Model ◽  
Middle Atmosphere ◽  
Meridional Circulation ◽  
Stratospheric Ozone ◽  
High Energy ◽  
Chemical Changes ◽  
Temperature Changes ◽  
Mesospheric Temperature ◽  
High Energy Electrons ◽  
Circulation Changes

Energetic particle precipitation (EPP) is known to be an important source of chemical changes in the polar middle atmosphere in winter. Recent modeling studies further suggest that chemical changes induced by EPP can also cause dynamic changes in the middle atmosphere. In this study, we investigated the atmospheric responses to the precipitation of medium-to-high energy electrons (MEEs) over the period 2005–2013 using the Specific Dynamics Whole Atmosphere Community Climate Model (SD-WACCM). Our results show that the MEE precipitation significantly increases the amounts of NOx and HOx, resulting in mesospheric and stratospheric ozone losses by up to 60% and 25% respectively during polar winter. The MEE-induced ozone loss generally increases the temperature in the lower mesosphere but decreases the temperature in the upper mesosphere with large year-to-year variability, not only by radiative effects but also by adiabatic effects. The adiabatic effects by meridional circulation changes may be dominant for the mesospheric temperature changes. In particular, the meridional circulation changes occasionally act in opposite ways to vary the temperature in terms of height variations, especially at around the solar minimum period with low geomagnetic activity, which cancels out the temperature changes to make the average small in the polar mesosphere for the 9-year period.

The Effects of High-Energy Electrons on the Charging of Spacecraft Dielectrics

1979 ◽  
Vol 26 (6) ◽  
pp. 5101-5106 ◽  
Author(s):  
M. J. Treadaway ◽  
C. E. Mallon ◽  
T. M. Flanagan ◽  
R. Denson ◽  
E. P. Wenaas
Keyword(s):  
High Energy ◽  
High Energy Electrons
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