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1.
Based on a theory developed previously, parametric interaction between space-charge waves in thin-film semiconductor structures with negative differential conductivity is analyzed. The analysis is carried out in the approximation that the drift flux of charge carriers has a rigid boundary and under the assumption that the frequency of low-frequency pumping equals the cutoff frequency f c of waves being amplified (f c roughly equals 30 GHz in our case). For asymmetric structures, a general multimode set of coupled equations is reduced to a pair of differential equations for the excitation amplitudes of the fundamental space-charge mode at the signal frequency ωs and idler frequency ωi=ωs−ωp. The equations are solved numerically for n-GaAs-based structures, and the solution obtained is discussed. 相似文献
2.
Results of a theoretical analysis of the influence of various factors on the efficiency of excitation of space-charge waves
in thin-film semiconductor structures by a single strip Schottky barrier are presented. It is shown that to increase the efficiency
of conversion of a microwave signal into space-charge waves, it is advisable to use a Schottky barrier with a small contact
potential with optimized values of the width of the Schottky barrier and the electron concentration in the film.
Zh. Tekh. Fiz. 69, 128–130 (January 1999) 相似文献
3.
An analysis is made of the region of existence of crystalline order in a system of spatially separated electrons (e) and holes (h) in two coupled quantum wells for various concentrations n, temperatures T, and distances D between the layers. A study is also made of crystallization in a system of electrons in semiconductor structures near a metal
electrode for various distances d between the semiconductor and the metal. Calculations of the crystalline phase were made using variational calculations of
the ground-state energy of the system allowing for pairing of quasiparticles with nonzero momentum. For a system of two coupled
quantum wells, regions in (T,n,D) space are determined in which electron (or hole) charge-density waves exist in each layer and regions where these charge-density
waves are in phase, in other words, indirect excitons (or pairs with spatially separated electrons and holes) interacting
as electric dipoles, become crystallized. In the electron system in semiconductor structures near a metal electrode, regions
of existence of an electron crystal are also obtained in (T,n,D) space, where over large distances the electrons interact as electric dipoles because of image forces.
Fiz. Tverd. Tela (St. Petersburg) 40, 1350–1355 (July 1998) 相似文献
4.
Collinear interaction of optical modes in a thin-film semiconductor waveguide with a space-charge wave increasing along its propagation direction has been investigated. Analytical solutions to the equations of coupled unidirectional and counterpropagating waveguide modes at their phase matching are obtained for the first time, and the dependence of the mode conversion efficiency on the space-charge wave amplification level, the coupling coefficient, and the length of the interaction region of optical modes is analyzed. 相似文献
5.
We study the interaction of a rectilinear nonrelativistic electron beam with a solid-state plasma in a rectangular metal waveguide, as well as wave processes in a plasma waveguide of rectangular cross section in the absence of an electron beam. It is shown that in such a system, space-charge waves of an electron beam, which propagate along a semiconductor boundary, become unstable in a wide frequency band.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 48, No. 3, pp. 219–227, March 2005. 相似文献
6.
Chen C. Danly B.G. Shvets G. Wurtele J.S. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1992,20(3):149-154
The influence of the longitudinal space-charge waves of a coherently gyrophased helical relativistic electron beam on the cyclotron maser instability is investigated in a cylindrical waveguide configuration using a three-dimensional kinetic theory. A dispersion relation that includes waveguide effects is derived. The stability properties of the cyclotron maser interaction are examined in detail. It is shown that, in general, the effects of space-charge waves on a coherently gyrophased beam are suppressed in a waveguide geometry, in comparison with an ideal one-dimensional cyclotron maser with similar beam parameters 相似文献
7.
Spin-wave structures with magnetic-field-driven current-voltage characteristics at room temperature were produced using a
spintronic europium-monoxide-based thin-film emitter and a single-crystal n-GaAs semiconductor collector. This manifests practical implementation of the spin current transport and creation of a high-temperature
spin transistor with the magnetic semiconductor/nonmagnetic semiconductor contact. 相似文献
8.
Chun-Yi Wang 《International Journal of Infrared and Millimeter Waves》1986,7(3):365-378
The cyclotron maser instability is conventionally treated as a pure electromagnetic instability(5). Waveguide modes can'be equivalent to plane waves reflected slantingly upon the two sides of the waveguide. According to the principles of plasma physics(6) the electromagnetic and the electrostatic modes can't be decoupled when the wave vector isn't strictly perpendicular or parallel to the d-c magnetic field. Therefore the conventional treatment is incomplete and invalid in the case of intense beams.Vlasov kinetic theory of the cyclotron maser instability taking into account the space-charge wave is presented. It is found that the respective couplings between the negative-energy cyclotron mode and the RHCP waveguide mode as well as the fast space-charge mode are responsible for the wave-guide maser instability. 相似文献
9.
Using quantum hydrodynamic (QHD) model and standard reductive perturbation method, we have investigated the formation and characteristics of space-charge solitary waves and double layers in n-type compensated drifting semiconductor plasma with varying doping profiles. Through numerical analysis, it is shown that the structures of space-charge solitary waves and double layers depend significantly on electron drift and compensation parameter which measures a comparative proportion of the donor, acceptor and intrinsic ion concentrations. 相似文献
10.
The effect of graded-band-gap layers on the differential resistance of space-charge region in MIS structures based on MBE
HgCdTe (x = 0.225) is examined. It is shown that the effect of resistance of the epitaxial-film bulk on the measured capacitance and
resistance should be taken into account for correct determination of space-charge region parameters. The presence of near-surface
layers with increased Cd contents results in an increase in the resistance of the space-charge region in strong inversion.
The product of semiconductor resistance by area as high as 15 Ω⋅cm2 is obtained despite suppression of tunnel generation-recombination through deep levels in MIS structures with graded-band-gap
layers. This might be due to background photogeneration and diffusion of minority charge carriers. The mechanisms for limitation
of the differential resistance of space-charge region at different temperatures are discussed for n-HgCdTe (x = 0.225 and 0.292) and p-HgCdTe (x = 0.225). 相似文献
11.
An exact numerical analysis is given of electron waves in a pair of coupled semiconductor heterojunction electron waveguides modelled by a rectangular potential distribution. The waveguide lengths required for electron current transfer between the guides agree asymptotically with estimates from Yariv's coupled mode theory and are usefully more accurate. Moreover the electron wave coupling due to an ideal launcher can be worked out, leading to estimates of the off/on current ratio occurring in the waveguides when regarded as an ultrafast switch. For a Poisson probability distribution of the number of electrons N making up a bit-pulse, we have calculated the minimum average N, dependent upon , which would be required to keep the switching bit-error rate below prescribed limits. Pulse rise times and switching delays are derived from the explicit forms for the longitudinal electron wave group velocity. Combining the bit-error and switching-time calculations leads to estimates of the waveguide current densities which would be required in practice. Some normalized sets of curves relating to our analysis are given and used to predict the performance of particular examples of recently proposed AlGaAs/GaAs heterojunction electron waveguide switch/couplers. 相似文献
12.
E. G. Alexov 《等离子体物理论文集》1995,35(1):23-32
Backward waves in waveguides completely filled with magnetoactive plasma (gaseous or semiconductor plasma) have been investigated numerically. It is shown that two types of backward waves exist in such waveguides: cyclotron backward waves and waveguide HE-modes. While the cyclotron modes are backward waves at arbitrary system parameters (plasma density, magnetic field and waveguide radius), the waveguide backward waves appear only at certain values of there parameters. In addition the cyclotron backward waves can propagate at arbitrary wave-number kz and at arbitrary phase velocity. The backward waveguide modes exist only at limited values of kz and of phase velocities. 相似文献
13.
A density-functional theory for (BAs)n clusters (n=1 14): structures, stabilities and electronic properties
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This paper investigates the lowest-energy structures,stabilities and electronic properties of (BAs) n clusters (n=1-14) by means of the density-functional theory.The results show that the lowest-energy structures undergo a structural change from two-dimensional to three-dimensional when n=4.With the increase of the cluster size (n 6),the (BAs) n clusters tend to adopt cage-like structures,which can be considered as being built from B 2 As 2 and six-membered rings with B-As bond alternative arrangement.The binding energy per atom,second-order energy differences,vertical electron affinity and vertical ionization potential are calculated and discussed.The caculated HOMO-LUMO gaps reveal that the clusters have typical semiconductor characteristics.The analysis of partial density of states suggests that there are strong covalence and molecular characteristics in the clusters. 相似文献
14.
The collinear interaction of optical waveguide modes is considered in a thin semiconductor layer containing an optical inhomogeneity (space-charge wave) growing along the wave-propagation direction. Coupled-mode equations are solved for the case where interacting waves propagate in the same direction or in opposite directions. The mode conversion efficiency is shown to depend substantially on the space-charge wave amplification with allowance for the detuning from the phase matching condition. The incident and the oppositely propagating modes can be “degenerate,” in which case the modes have the same power over the entire disturbed region. 相似文献
15.
J.J. Quinn 《Solid State Communications》1984,52(6):607-609
The electronic collective excitations are investigated for a number of different systems whose equilibrium electron density n0(z) is spatially varying. The relation between higher multipole surface modes, waveguide like plasma modes of a low electron density layer embedded in a high density host, and plasmon bands of periodic metallic heterostructures and semiconductor superlattices is pointed out. 相似文献
16.
The paper describes the solution for the space-charge capacitance in thin semiconductor films under general boundary conditions. The influence of both surfaces and film thickness on this capacitance is discussed in more detail and it is shown that cases exist in which the space-charge capacitance depends on the properties of one surface or on the film thickness only.Notation
E
s2
dimensionless surface field intensity
-
F
1, F2, F3
space-charge functions
-
k
Boltzmann's constant
-
n
bulk electron density
-
p
b
bulk hole density
-
q
electron charge
-
T
absolute temperature
-
o
permittivity of free space
-
s
relative permittivity of semiconductor
-
dimensionless thicknessd/L
D
-
dimensionless coordinate perpendicular to the surfacez/L
D
-
dimensionless potential (multiples ofkT/q). 相似文献
17.
A high-power sub-millimeter wave propagating through bismuth, a semimetal with non-spherical energy surfaces, parametrically excites a space-charge mode and a back-scattered electromagnetic wave. The free carrier density perturbation associated with the space-charge wave couples with the oscillatory velocity due to the pump to derive the scattered wave. The scattered and pump waves exert a pondermotive force on electrons and holes, driving the space-charge wave. The collisional damping of the decay waves determines the threshold for the parametric instability. The threshold intensity for 20 μm wavelength pump turns out to be ∼2×1012 W/cm2. Above the threshold, the growth rate scales increase with ωo, attain a maximum around ωo=6.5ωp, and, after this, falls off. 相似文献
18.
A. F. Bunkin M. A. Davydov V. G. Mikhalevich S. M. Pershin V. N. Streltsov 《Physics of Wave Phenomena》2016,24(4):282-287
Probe-beam scattering spectra have been obtained for four-wave mixing of laser waves in the skin layer of intrinsic semiconductors. The spectra were recorded using the frequency dispersion of orthogonally polarized radiation, which arises as a result of nonlinear optical interaction with conduction-band electrons. The mixing of two counterpropagating light waves in a semiconductor, implemented under nonlinear excitation of longitudinal density oscillations in the plasma electron subsystem of the semiconductor, is theoretically considered. This mixing is shown to lead to the rotation of the probe-beam polarization vector. The results obtained are of interest, e.g., for studying optical metamaterials based on thin-film structures. 相似文献
19.
We present experimental observations of the abnormal growth of localized nonlinear space-charge waves in space-charge dominated electron beams passing through a resistive channel. The energy width of the space-charge waves is measured on both ends of the channel. Previous experiments had shown that, for small initial perturbations, the energy width of the slow waves increases, while the energy width of the fast waves decreases, in agreement with linear theory. We report that in the nonlinear regime (large initial perturbations), the energy width of the fast wave increases, which is unexpected, and, to the best of our knowledge, no theory exists that would predict this phenomenon. 相似文献