Intermittency route to chaos and broadband high-frequency generation in semiconductor superlattice coupled to external resonator

We investigate the onset of broadband microwave chaos in the miniband semiconductor superlattice coupled to an external resonator. Our analysis shows that the transition to chaos, which is confirmed by calculation of Lyapunov exponents, is associated with the intermittency scenario. The evolution of the laminar phases and the corresponding Poincare maps with variation of a supercriticality parameter suggest that the observed dynamics can be classified as type I intermittency. We study the spatiotemporal patterns of the charge concentration and discuss how the frequency band of the chaotic current oscillations in semiconductor superlattice depends on the voltage applied

Bifurcation phenomena in a semiconductor superlattice subject to a tilted magnetic field

The paper studies instabilities of charge transport in strongly coupled semiconductor superlattices with an applied electric and a tilted magnetic field. We reveal the bifurcation phenomena, which are associated with the transitions between different regimes of charge dynamics, and also investigate effects of the temperature on these bifurcations. In addition, we find out that the development of an instability can be accompanied by a graduate change of the dominant transport mechanism

Lyapunov analysis of the spatially discrete-continuous system dynamics

The spatially discrete-continuous dynamical systems, that are composed of a spatially extended medium coupled with a set of lumped elements, are frequently met in different fields, ranging from electronics to multicellular structures in living systems. Due to the natural heterogeneity of such systems, the calculation of Lyapunov exponents for them appears to be a challenging task, since the conventional techniques in this case often become unreliable and inaccurate. The paper suggests an effective approach to calculate Lyapunov exponents for discrete-continuous dynamical systems, which we test in stability analysis of two representative models from different fields. Namely, we consider a mathematical model of a 1D transferred electron device coupled with a lumped resonant circuit, and a phenomenological neuronal model of spreading depolarization, which involves 2D diffusive medium. We demonstrate that the method proposed is able reliably recognize regular, chaotic and hyperchaotic dynamics in the systems under study

Lyapunov stability of charge transport in miniband semiconductor superlattices

We discuss a numerical method for the calculation of the spectrum of Lyapunov exponents for spatially extended systems described by coupled Poisson and continuity equations. This approach was applied to the model of collective charge transport in semiconductor superlattices operating in the miniband transport regime. The method is in very good agreement with analytical results obtained for the steady state. As an illustrative example, we consider the collective electron dynamics in the superlattice subjected to an ac voltage and a tilted magnetic field, and conclusively show that, depending on the field parameters, the dynamics can exhibit periodic, quasiperiodic, or chaotic behavior

ВЛИЯНИЕ МЕЖМИНИЗОННОГО ТУННЕЛИРОВАНИЯ НА ГЕНЕРАЦИЮ ТОКА В ПОЛУПРОВОДНИКОВОЙ СВЕРХРЕШЕТКЕ

В работе теоретически изучeнo влияние ширины запрещенной зоны между первой и второй энергетическими минизонами на транспорт заряда в полупроводниковой сверхрешетке, к которой приложены электрическое и наклонное магнитные поля. Были рассчитаны временные зависимости тока, протекающего через сверхрешетку, и построены зависимости амплитуды и частоты колебаний электрического тока от приложенного напряжения. Обнаружено, что межминизонное туннелирование электронов способствует уменьшению амплитуды колебаний тока, но в тоже время увеличивает их частоту

Effect of temperature on resonant electron transport through stochastic conduction channels in superlattices

We show that resonant electron transport in semiconductor superlattices with an applied electric and tilted magnetic field can, surprisingly, become more pronounced as the lattice and conduction electron temperature increases from 4.2 K to room temperature and beyond. It has previously been demonstrated that at certain critical field parameters, the semiclassical trajectories of electrons in the lowest miniband of the superlattice change abruptly from fully localized to completely unbounded. The unbounded electron orbits propagate through intricate web patterns, known as stochastic webs, in phase space, which act as conduction channels for the electrons and produce a series of resonant peaks in the electron drift velocity versus electric-field curves. Here, we show that increasing the lattice temperature strengthens these resonant peaks due to a subtle interplay between the thermal population of the conduction channels and transport along them. This enhances both the electron drift velocity and the influence of the stochastic webs on the current-voltage characteristics, which we calculate by making self-consistent solutions of the coupled electron transport and Poisson equations throughout the superlattice. These solutions reveal that increasing the temperature also transforms the collective electron dynamics by changing both the threshold voltage required for the onset of self-sustained current oscillations, produced by propagating charge domains, and the oscillation frequency

Space charge dynamics in a semiconductor superlattice affected by titled magnetic field and heating

© 2016, Allerton Press, Inc.The transition between different modes of current oscillations in a semiconductor superlattice, from close-to-harmonic (near the generation onset) to relaxation oscillations, has been investigated. The transition type is shown to change with an increase in temperature. A period-doubling bifurcation is observed at low temperatures. With an increase in temperature, the period-doubling bifurcation is observed at increasingly larger values of the voltage across the superlattice. The doubling bifurcation ceases to be observed at voltages at which the generation of oscillations of the current through the semiconductor superlattice is suppressed

The effect of collector doping on the high-frequency generation in strongly coupled semiconductor superlattice

This letter focuses on the analysis of the spatio-temporal dynamics of charge domains in strongly coupled semiconductor superlattices with the Ohmic emitter and collector contacts. Our numerical simulations, based on the semiclassical approximation of the electron transport, show that the collector doping can dramatically affect the charge dynamics in the semiconductor structure and, therefore, the output AC power. We demonstrate that the appropriately chosen doping of the collector contacts can considerably increase the power of the generated signal

ИССЛЕДОВАНИЕ ПЕРЕХОДОВ МЕЖДУ РАЗЛИЧНЫМИ РЕЖИМАМИ ГЕНЕРАЦИИ КОЛЕБАНИЙ ТОКА В ПОЛУПРОВОДНИКОВОЙ СВЕРХРЕШЕТКЕ В ПРИСУТСТВИИ НАКЛОННОГО МАГНИТНОГО ПОЛЯ ПРИ РАЗЛИЧНЫХ ТЕМПЕРАТУРАХ [Studying transitions between different regimes of current oscillations generated in a semiconductor superlattice in the presence of a tilted magnetic field at various temperatures]

В настоящей работе исследуются механизмы переходов между различными режимами колебаний в полупроводниковой сверхрешетке в присутствии внешнего наклонного магнитного. В случае небольших температур с ростом напряжения в системе происходит бифуркация удвоения периода, обуславливающая смену динамического режима, тогда как с увеличением температуры переход осуществляется через срыв генерации колебаний тока. [The mechanisms of transitions between different regimes of current oscillations in a semiconductor superlattice in the presence of a tilted magnetic field at various temperatures have been studied. At relatively low temperatures, an increase in the applied voltage leads to a period -doubling bifurcation that causes a change in the dynamic regime. At increased temperatures, the transition takes place with the quenching of current oscillations.

Spatial distribution of electric field in a quantum superlattice with an injecting contact: exact solution

[English abstract unavailable.