scholarly journals Локализация электронов верхних долин в узкозонном канале --- возможный дополнительный механизм увеличения тока в DA-DpHEMT

2019 ◽  
Vol 45 (20) ◽  
pp. 11
Author(s):  
А.Б. Пашковский ◽  
С.А. Богданов
Keyword(s):  
Drift Velocity ◽  
Narrow Band ◽  
Wide Band ◽  
Acceptor Doping ◽  
Additional Mechanism ◽  
Velocity Increase ◽  
Velocity Overshoot ◽  
Donor Acceptor ◽  
Band Material ◽  
Localization Of Electrons

Abstract: The theoretical estimation of the effect of electron localization in the upper valleys in the narrow-band channel of transistor heterostructures AlxGa1–xAs-GaAs with two-sided doping on the value оf drift velocity overshoot is carried out. It is shown that for transistor heterostructures with donor-acceptor doping, in which the proportion of electrons transferred from the narrow-band channel to the wide-band material is less than in conventional structures, in some cases, the drift velocity increase can reach 15 % due to the localization of electrons in the upper valleys in the narrow-band channel. The studied effect can be an additional mechanism for increasing the current in transistors based on heterostructures with donor-acceptor doping.

Syntheses and Photovoltaic Properties of Narrow Band Gap Donor–Acceptor Copolymers with Carboxylate-Substituted Benzodithiophene as Electron Acceptor Unit

2014 ◽  
Vol 47 (15) ◽  
pp. 4987-4993 ◽  
Author(s):  
Kosuke Shibasaki ◽  
Kenichi Tabata ◽  
Yohei Yamamoto ◽  
Takeshi Yasuda ◽  
Masashi Kijima
Keyword(s):  
Band Gap ◽  
Electron Acceptor ◽  
Narrow Band ◽  
Photovoltaic Properties ◽  
Donor Acceptor

Spread-of-Masking Effects on Pure Tones and Several Speech Stimuli

1973 ◽  
Vol 16 (3) ◽  
pp. 385-396
Author(s):  
Richard H. Wilson ◽  
Richard W. Stream ◽  
Donald D. Dirks
Keyword(s):  
Pure Tone ◽  
Narrow Band ◽  
Wide Band ◽  
Intensity Level ◽  
Speech Stimuli ◽  
Intensity Range ◽  
Speech Spectrum ◽  
Series Of Experiments ◽  
Pure Tones ◽  
Upper Slope

A series of experiments was performed to study the upward-spread-of-masking phenomena as it pertains to pure-tone and speech stimuli. In the initial two experiments, three maskers were employed over a 40–60-dB intensity range. They included a wide band (50–5500 Hz), a speech spectrum (50–1000 Hz), and a narrow-band (50–950 Hz) noise. All filter slopes were 48 dB/octave, except for the upper slope of the speech-spectrum noise that was 6 dB/octave. In the first experiment, pure-tone thresholds obtained by a tracking procedure revealed no spread of masking when the wide-band and speech-spectrum maskers were used. Substantial spread-of-masking effects, characterized by nonlinear threshold increments outside the spectrum of the masker, were observed with the narrow-band masker. The second experiment included three types of speech stimuli (PBs, spondees, and synthetic sentences) under the same mask conditions used with the pure tones. Threshold shifts observed for the wide- and speech-spectrum maskers were linear with the masking intensity level. However, increased shifts, attributable to spread of masking, were observed with the narrow band and progressed nonlinearly as a function of the masking level. Finally, two additional experiments, performed with two different narrow-band maskers and spondee words, provided insightful information regarding the effects of the spread of masking on speech stimuli.

scholarly journals Увеличение насыщенной скорости дрейфа электронов в pHEMT-гетероструктурах с донорно-акцепторным легированием

2018 ◽  
Vol 44 (6) ◽  
pp. 77
Author(s):  
Д.Ю. Протасов ◽  
Д.В. Гуляев ◽  
А.К. Бакаров ◽  
А.И. Торопов ◽  
Е.В. Ерофеев ◽  
...  
Keyword(s):  
Drift Velocity ◽  
High Electron Mobility Transistor ◽  
Real Space ◽  
Electron Drift Velocity ◽  
Hot Electrons ◽  
Electron Drift ◽  
High Electron ◽  
High Electron Mobility ◽  
Donor Acceptor ◽  
Real Space Transfer

AbstractField dependences of the electron-drift velocity in typical pseudomorphic high-electron-mobility transistor (pHEMT) heteroepitaxial structures (HESs) and in those with donor–acceptor doped (DApHEMT) heterostructures with quantum-well (QW) depth increased by 0.8–0.9 eV with the aid of acceptor layers have been studied by a pulsed technique. It is established that the saturated electron-drift velocity in DA-pHEMT-HESs is 1.2–1.3 times greater than that in the usual pHEMT-HESs. The electroluminescence (EL) spectra of DA-pHEMT-HESs do not contain emission bands related to the recombination in widebandgap layers (QW barriers). The EL intensity in these HESs is not saturated with increasing electric field. This is indicative of a suppressed real-space transfer of hot electrons from QW to barrier layers, which accounts for the observed increase in the saturated electron-drift velocity.

COMPARISON OF TRANSIENT BALLISTIC ELECTRON TRANSPORT IN BULK WURTZITE PHASE 6H-SiC and GaN

2008 ◽  
Vol 22 (30) ◽  
pp. 5289-5297 ◽  
Author(s):  
H. ARABSHAHI
Keyword(s):  
Conduction Band ◽  
Drift Velocity ◽  
Velocity Ratio ◽  
Ballistic Transport ◽  
Energy Separation ◽  
Wurtzite Phase ◽  
Velocity Overshoot ◽  
Ballistic Electron ◽  
Ballistic Electron Transport ◽  
Transient Velocity

An ensemble Monte Carlo simulation is used to compare bulk electron ballistic transport in 6H - SiC and GaN materials. Electronic states within the conduction band valleys at Γ1, U, M, Γ3, and K are represented by nonparabolic ellipsoidal valleys centered on important symmetry points of the Brillouin zone. The large optical phonon energy (~120 meV) and the large intervalley energy separation between the Γ and satellite conduction band valleys suggest an increasing role for ballistic electron effects in 6H - SiC , especially when compared with most III-V semiconductors such as GaAs . Transient velocity overshoot has been simulated, with the sudden application of fields up to ~5×107 Vm -1, appropriate to the gate-drain fields expected within an operational field effect transistor. A peak-saturation drift velocity ratio of 2:1 is predicted for 6H - SiC material while that for GaN is 4:1. The electron drift velocity relaxes to the saturation value of ~2×105 ms -1 within 3 ps, for both crystal structures. The transient velocity overshoot characteristics are in fair agreement with other recent calculations.

Full-Spectrum k-Distribution Model for Radiation in Gas Based on Multi-Group Methods

2014 ◽  
Vol 1008-1009 ◽  
pp. 839-845
Author(s):  
Yue Zhou ◽  
Qiang Wang ◽  
Hai Yang Hu
Keyword(s):  
Narrow Band ◽  
Wide Band ◽  
Distribution Model ◽  
Full Spectrum ◽  
Distribution Method ◽  
One Dimensional ◽  
Group Methods ◽  
Monotonically Increasing Function ◽  
Homogeneous Media ◽  
Increasing Function

The k-distribution method applied in narrow band and wide band is extended to the full spectrum based on spectroscopic datebase HITEMP, educing the full-spectrum k-distribution model. Absorption coefficents in this model are reordered into a smooth,monotonically increasing function such that the intensity calculations are performed only once for each absorption coefficent value and the resulting computations are immensely more efficent.Accuracy of this model is examined for cases ranging from homogeneous one-dimensional carbon dioxide to inhomogeneous ones with simultaneous variations in temperature. Comparision with line-by-line calculations (LBL) and narrow-band k-distribution (NBK) method as well as wide-band k-distribution (WBK) method shows that the full-spectrum k-distribution model is exact for homogeneous media, although the errors are greater than the other two models. After dividing the absorption coefficients into several groups according to their temperature dependence, the full-spectrum k-distribution model achieves line-by-line accuracy for gases inhomogeneous in temperature, accompanied by lower computational expense as compared to NBK model or WBK model. It is worth noting that a new grouping scheme is provided in this paper.

Efficient Multirate Filtering

2002 ◽  
pp. 105-142 ◽  
Author(s):  
Ljiljana D. Milic ◽  
Miroslav D. Lutovac
Keyword(s):  
Digital Filter ◽  
Filter Design ◽  
Narrow Band ◽  
Sampling Rate ◽  
Wide Band ◽  
Digital Filter Design ◽  
Iir Filter ◽  
Design And Implementation ◽  
Sampling Rate Conversion ◽  
Rate Conversion

Application of multirate techniques to improve digital filter design and implementation are considered in this chapter. FIR and IIR filter design and implementation for sampling rate conversion by integer and rational factors are presented. Sharp narrow-band and wide-band multirate design techniques are discussed. Accurate designs of FIR and IIR half-band filters are described in detail. Several examples are provided to illustrate the multirate approach to filter design.

Increasing Saturated Electron-Drift Velocity in Donor–Acceptor Doped pHEMT Heterostructures

2018 ◽  
Vol 44 (3) ◽  
pp. 260-262 ◽  
Author(s):  
D. Yu. Protasov ◽  
D. V. Gulyaev ◽  
A. K. Bakarov ◽  
A. I. Toropov ◽  
E. V. Erofeev ◽  
...  
Keyword(s):  
Drift Velocity ◽  
Electron Drift Velocity ◽  
Electron Drift ◽  
Donor Acceptor
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