Low-frequency dispersion properties of plasmas with variable-charge impurities

2000 ◽  
Vol 7 (2) ◽  
pp. 461-465 ◽  
Author(s):  
K. N. Ostrikov ◽  
S. V. Vladimirov ◽  
M. Y. Yu ◽  
G. E. Morfill
Keyword(s):  
Low Frequency ◽  
Frequency Dispersion ◽  
Dispersion Properties ◽  
Variable Charge

scholarly journals Identification of Buffer and Surface Traps in Fe-Doped AlGaN/GaN HEMTs Using Y21 Frequency Dispersion Properties

Electronics ◽  
2021 ◽  
Vol 10 (24) ◽  
pp. 3096
Author(s):  
P. Vigneshwara Raja ◽  
Nandha Kumar Subramani ◽  
Florent Gaillard ◽  
Mohamed Bouslama ◽  
Raphaël Sommet ◽  
...  
Keyword(s):  
Low Frequency ◽  
Frequency Dispersion ◽  
Drain Current ◽  
Surface Region ◽  
Electron Trap ◽  
High Electron ◽  
Trap States ◽  
Dispersion Properties ◽  
Donor States ◽  
Surface Donor

The buffer and surface trapping effects on low-frequency (LF) Y-parameters of Fe-doped AlGaN/GaN high-electron mobility transistors (HEMTs) are analyzed through experimental and simulation studies. The drain current transient (DCT) characterization is also carried out to complement the trapping investigation. The Y22 and DCT measurements reveal the presence of an electron trap at 0.45–0.5 eV in the HEMT structure. On the other hand, two electron trap states at 0.2 eV and 0.45 eV are identified from the LF Y21 dispersion properties of the same device. The Y-parameter simulations are performed in Sentaurus TCAD in order to detect the spatial location of the traps. As an effective approach, physics-based TCAD models are calibrated by matching the simulated I-V with the measured DC data. The effect of surface donor energy level and trap density on the two-dimensional electron gas (2DEG) density is examined. The validated Y21 simulation results indicate the existence of both acceptor-like traps at EC –0.45 eV in the GaN buffer and surface donor states at EC –0.2 eV in the GaN/nitride interface. Thus, it is shown that LF Y21 characteristics could help in differentiating the defects present in the buffer and surface region, while the DCT and Y22 are mostly sensitive to the buffer traps.

Magnetic Permeability and Relaxation Frequency in High Frequency Magnetic Materials.

2001 ◽  
Vol 674 ◽  
Author(s):  
M.I. Rosales ◽  
H. Montiel ◽  
R. Valenzuela
Keyword(s):  
High Frequency ◽  
Domain Walls ◽  
Magnetocrystalline Anisotropy ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Anisotropy Constant ◽  
Relaxation Frequency ◽  
Resonance Relaxation ◽  
Frequency Behavior

ABSTRACTAn investigation of the frequency behavior of polycrystalline ferrites is presented. It is shown that the low frequency dispersion (f < 10 MHz) of permeability is associated with the bulging of pinned domain walls, and has a mixed resonance-relaxation character, closer to the latter. It is also shown that there is a linear relationship between the magnetocrystalline anisotropy constant, K1, and the relaxation frequency. The slope of this correlation depends on the grain size. Such a relationship could allow the determination of this basic parameter from polycrystalline samples.

Volume low-frequency dispersion in a semi-insulating system

1988 ◽  
Vol 23 (2) ◽  
pp. 209-213 ◽  
Author(s):  
A.K. Jonscher ◽  
L. Levesque
Keyword(s):  
Low Frequency ◽  
Frequency Dispersion

Theory of the ferroelectric Mott-Hubbard phase in organic conductors

2002 ◽  
Vol 12 (9) ◽  
pp. 149-152
Author(s):  
S. Brazovskii
Keyword(s):  
Activation Energy ◽  
Phase Transitions ◽  
Low Frequency ◽  
Frequency Dispersion ◽  
Organic Conductors ◽  
The State ◽  
Charge Disproportionation ◽  
Subsequent Phase

Recently the ferroelectric FE anomaly (Nad, Monceau, et al.) followed by the charge disproportionation CD (Brown, et al) have been discovered in ($TMTTF)_2X$ compounds. A theory of the combined Mott-Hubbard state describes both effects by interference of the build-in nonequivalence of bonds and the spontaneous one of sites. The state gives rise to three types of solitons: $\pi -$ solitons (holons) are observed via the activation energy A in conductivity G; noninteger $\alpha -$ solitons provide the frequency dispersion of the FE response; combined spin-charge solitons determine $G(T)$ below subsequent phase transitions. The optical edge lies well below the conductivity gap 2A; the critical FE mode coexists with a combined electron-phonon resonance and a phonon antiresonance. The CD and the FE can exists hiddenly even in the Se subfamily giving rise to the unexplained yet low frequency optical peak, the enhanced pseudogap and traces of phonons activation.

scholarly journals Bioimpedance Analysis of L929 and HaCaT Cells in Low Frequency Range

2018 ◽  
Vol 4 (1) ◽  
pp. 115-118 ◽  
Author(s):  
Viviane S. Teixeira ◽  
Jan-Patrick Kalckhoff ◽  
Wolfgang Krautschneider ◽  
Dietmar Schroeder
Keyword(s):  
Low Frequency ◽  
Steel Corrosion ◽  
Frequency Dispersion ◽  
Human Keratinocytes ◽  
Cell Types ◽  
Hacat Cells ◽  
Frequency Range ◽  
Corrosion Resistant ◽  
L929 Mouse

AbstractIn this work, Bioimpedance Spectroscopy (BIS) is used to study fluids and cell solutions. A n ew fourelectrode- terminal (4T) chamber using 3D printing and stainless steel corrosion resistant V4A was designed to measure the impedance of live cell solutions at the frequency range 0.1Hz- 1MHz. At f < 1kHz the double layer (DL) that builds at electrode’s surface raises the impedance substantially preventing the observation of the real impedance of the cells. The new 4T design circumvents the DL, is more robust and cheap, and allows for the repeatability of the results. Experiments were performed in vitro with two cell lines, L929 (mouse fibroblasts) and HaCaT (human keratinocytes). Results show that it is possible to distinguish between the two cell types by means of its BIS measurements in the new setup. Also, a low-frequency dispersion (α-dispersion) was observed in HaCaT cells solution, but not in L929. Furthermore, a potentiostat circuit model was developed in LTSpice to simulate the hardware setup and two different circuit models were used to fit cell’s data.

Low-frequency dispersion characteristics of GaN HFETs

1995 ◽  
Vol 31 (22) ◽  
pp. 1951-1952 ◽  
Author(s):  
W. Kruppa ◽  
K. Doverspike ◽  
S.C. Binari
Keyword(s):  
Low Frequency ◽  
Frequency Dispersion ◽  
Dispersion Characteristics
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