Absorption of a strong electromagnetic wave by electrons in a superlattice in a quantizing electric field

Intraminiband absorption of light by electrons in a quantum superlattice in a quantizing electric field is investigated theoretically taking into account the electron-phonon interaction. It is assumed that the interaction with optical dispersion-free phonons makes the main contribution to electron scattering. It is shown that the point ω=ω ₀ (ω is the light frequency, and ω ₀ is the optical phonon frequency) conditionally divides the ω dependence of the absorption into two parts: ω<ω ₀, the region of exponentially weak absorption and ω>ω ₀, the region of “strong” absorption. An electric field shifts the region of strong absorption in the red direction of the spectrum. Fiz. Tekh. Poluprovodn. 33, 1355–1358 (November 1999)     

Effect of a transverse electric field on charge carrier mobility in nanowires

For nanowires with a parabolic potential, the effect of an electric field E orthogonal to the system??s axis on the mobility of charge carriers ?? is investigated. With consideration for the interaction of charge carriers with a rough surface, it is shown that, for a nondegenerate electron (hole) gas, the mobility ?? decreases with increasing E. For a degenerate electron (hole) gas, the dependence of ?? on E is described by a nonmonotonic oscillating function. A physical interpretation of the predicted effect is proposed.     

Electron-photon drag effect in a semiconductor superlattice subjected to a high electric field

Drag of charge carriers in a superlattice subjected to a constant axially oriented electric field by an electromagnetic wave also propagating along the axis is considered. The drag-current density is calculated and its dependence on the constant-field strength E₁ and the electromagnetic-wave intensity I is analyzed. Reversals of the current direction are found to occur for certain values of E₁ and I.     

Studies of the mobility of charge carriers in low-dimensional systems in a transverse DC electric field

The mobility of charge carriers μ in a parabolic quantum well in an electric field E directed along the size-confinement axis is calculated. With consideration for scattering of charge carriers at a rough surface, the mobility μ is shown to decrease with increasing E. A physical interpretation of this effect is proposed.     

Temperature dependence of thermoelectric power in n-InSb in a transverse quantizing magnetic field

The thermoelectric power in n-InSb in a transverse quantizing magnetic field has been studied in the temperature range 67–160 K. The dependence of the electronic component of the thermoelectric power on the magnetic field is accounted for in terms of a quantum theory taking into account the spin splitting of Landau levels.     

The influence of a nonlinear electromagnetic wave on electric current density in a surface superlattice in a strong electric field

The current density in a combination of a 2D electron gas and a superlattice subjected to a strong electric field under exposure to a cnoidal electromagnetic wave is studied, with electron-phonon coupling explicitly taken into account. A dc electric quantizing field is directed along the superstructure axis, with the vector of the field strength of the nonlinear wave being perpendicular to this axis. It is found that the constant component of the current density along the superlattice axis is oscillatory and depends on the electric field strength.     

Thermoelectric power of the n-InSb in a transverse quantizing magnetic field at a large temperature gradient

The thermoelectric power of the n-type indium antimonide was studied in the transverse magnetic field (0–80 kOe) at T _aV =160 K and different temperature gradients. It was found that the electron component of the thermoelectric power at a small temperature gradient is consistent with the theory that takes into account the electron spin, whereas, for a large temperature gradient, the value determined by the variation of the Benedicks thermoelectric power in the magnetic field is added to this component.     

Dynamic effect of a constant electric field on the kinetics of photons interacting with electrons in a semiconductor

The Liouville-von Neumann equation and a nonequilibrium statistical operator were used to derive a kinetic equation for photons that interact with nonrelativistic electrons in a constant electric field. The collision integral is nonvanishing due to the effect of the field on the interaction of photons with electrons. The probabilities that photons are absorbed or emitted depend on the photon frequency and on the component of the electric field along the photon-momentum direction; these dependences may either obey the power law or be oscillatory. The oscillations are related to the energy-time uncertainty relation. The contribution of this effect to the photon spectrum in reference to the emission accompanying the scattering of electrons by phonons and ionized impurities is calculated for n-GaAs. The range of parameters for which this effect may significantly affect the spectrum is determined.     

Effect of a bichromatic electric field on the current-voltage characteristic of a graphene-based superlattice

The longitudinal current-voltage characteristic of a graphene-based superlattice in high-frequency electric fields, such that the strength of one of the fields oscillates along the superlattice axis and the strength of the other perpendicularly to this axis, is calculated. It is shown that, if there is a transverse high-frequency field only, there exists a possibility for sharply increasing the current density in the negative-differential-conductivity region of the static current-voltage characteristic of the superlattice. The current density exhibits a jump, if the oscillation frequency of the field strength approaches the Bloch oscillation frequency. It is shown that, in such a situation, absorption of an electromagnetic wave in the graphene-based superlattice gives way to amplification.     

Two-dimensional electrons in a magnetic superlattice

We report on the motion of two-dimensional electrons in a magnetic field which is periodic on the scale of a few hundred nanometres. Such a system exhibits novel magnetoresistance oscillations that we unambiguously identify as due to a commensurability effect between the period of the magnetic field and the diameter of the cyclotron orbit. We find that a semiclassical picture of electron motion can quantitatively describe all of the observed experimental features. We also propose methods of optimizing the effects of the magnetic modulation in hybrid semiconductor-superconductor devices.     

Coupled plasma waves in a system of two two-dimensional superlattices in the presence of a quantizing electric field

The effect of a dc electric field on coupled plasma waves in a system of two two-dimensional super-lattices is studied. In the case of high temperatures, a dispersion relation is obtained and the fundamental and resonant modes of the plasma waves are numerically studied. The calculations are performed based on the quantum theory of plasma waves in the random phase approximation taking into account umklapp processes.     

Effect of transverse electric field on nyquist noise

According to Nyquist's theorem, in the low frequency limit, the thermal noise voltage spectrum can be written as S_v(f) = 4 kTR. Based on this, we can define, R_Nyquist = S_c(f)/4 kT as the Nyquist resistance of the sample. We can also define the observed zero bias resistance of a sample as $\text{R}{}_{\mathrm{observed}}\text{=}\text{lim}\text{V}\text{→o}\text{(V/I)}$ (V/I). It is common practice to substitute R_observed for R_Nyquist in order to estimate the thermal noise. It will be shown that this substitution is not always valid in MOSFETs, and that the data obtained by Takagi and van der Ziel can be explained in this manner.     

相对论电子在周期磁场中的辐射频谱

分析了相对论电子在空间周期磁场中的运动轨迹.在一定条件下,电子在垂直原始入射方向上的运动是简谐的,利用谐振子模型求出了它的辐射频谱和频宽;最后讨论了运动的非谐性.得到辐射频谱分布将是与电子的初速度、磁场强度有关.     

Longitudinal and transverse waves of the electric field

The importance and features of longitudinal and transverse waves of electric fields in various electric processes and technological applications of these waves are shown. The relationship between longitudinal and transverse waves of electric fields and the relationship between these waves and their sources are theoretically justified.     

Generation of transverse direct current in a superlattice under a bichromatic high-frequency electric and constant magnetic fields

Direct-current generation in a semiconductor superlattice exposed to a high-frequency bichromatic electric field applied along its axis and to a constant magnetic field perpendicular to the surface, i.e., superlattice axis, is studied. In the first non-vanishing approximation in terms of the magnetic-field strength, an explicit expression for the current density in the case of the ratio of electric-field frequencies equal to two is derived.     

Transformation kinetics of electric field domains in weakly coupled GaAs/AlGaAs superlattices in a transverse electric field

Transformation kinetics of the resonant-tunneling domain structure in a superlattice in a rapidly varying electric field is investigated using real-time studies of current response. It is shown that the kinetics is mainly determined by a lag in redistribution of the space charge that forms the domain boundary. A nonmonotonic oscillatory dependence of the transient-process duration on the amplitude of a voltage pulse is observed, as well as the effect of the weak dependence of the transformation time on the displacement of the domain boundary, which indicates that the transformation processes is discrete. Possibilities for controlling the switching processes in a multistable system of current states in weakly coupled semiconductor superlattices are discussed.     

Resonance propagation of electrons through three-barrier structures in a two-frequency electric field

The solution of the Schrödinger equation that describes resonance transitions between three equidistant quantum levels in asymmetric three-barrier resonance-tunnel structures in a high one-frequency electric field is extended to the case of differently separated levels and a two-frequency field, with the frequencies corresponding to resonance transitions in each of the coupled quantum wells. It is shown that, in the conditions of coherent electron transport, irrespective of the parameters of the structure, for any amplitude of the high resonance field in one well, there exists an amplitude of the resonance field in the other well such that the structure is absolutely transparent and most electrons (in the limiting case, all electrons) incident on the upper resonance level can emit two photons with different frequencies and leave the structure through the lower level with no intermediate interaction with phonons. The probability of the transitions substantially depends on the amplitudes of the fields and does not depend on the phase difference between the fields. It is found that the possibility exists of almost complete blocking of resonance transitions in one of the wells by a high-frequency field in the other well.     

Spin response of 2D electrons to a lateral electric field

The spin orientation of two-dimensional (2D) electrons by a lateral electric field is considered. The electron dispersion law is assumed to contain linear terms due to the spin-orbit band splitting in an asymmetric quantum well. The coefficient of spin orientation in a DC electric field is found. The mean electron spin is oriented in the sample plane perpendicularly to the electric field. The interaction of an AC electric field with spins of 2D electrons is studied. It is shown that transitions between different spin states give rise to a narrow absorption band. These states are mixed with 2D plasmons in the frequency range related to these transitions, with the result being that the plasmon spectrum is modified and a new type of oscillations arises (spin-plasmon polariton). The problem of the generation of spin-plasmon polaritons by an external field is solved.     

工频电场对ADSS光缆特性的影响

随着电压等级的不断提高,超高压输电线路发展非常迅速.但是这些架空输电线路在运行时,附近存在较高的电场,对周围物体和公用走廊的其它线路会产生影响.电压等级越高,产生的电场影响越大.输电线路产生的电场越来越受到人们的重视.尤其是对于超高压输电线路,由于在电力铁塔上同塔悬挂全介质自承式光缆(ADSS),因此分析工频电场对ADSS光缆特性的影响非常必要.     

Simulations of electric field domain suppression in a superlattice oscillator device using a distributed circuit model

We present a method for simulating static domain formation in distributed negative differential resistance devices using a distributed circuit array model coupled with quantum transport simulations. This simulation method is applied to the case of a superlattice Bloch oscillator to ascertain the efficacy of electric field domain wall suppression by micro shunt side walls. Two independent simulation mechanisms using the same basic distributed circuit model are employed to separate simulation artifacts from true physical trends. Simulations are presented, suggesting that the presence of the micro shunt can suppress domain formation above a critical device bias voltage. The simulated dependence of this critical voltage on macroscopic device parameters is presented.