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

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

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

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

[English abstract unavailable.

Electric-field distribution in a quantum superlattice with an injecting contact: exact solution [original Russian text]

A very simple model describing steady-state electron transport along a quantum superlattice of a finite length taking into account an arbitrary electrical characteristic of the injecting contact is considered. In the singleminiband approximation, exact formulas for the spatial distribution of the electric field in the superlattice are derived for different types of contact. Conditions under which the field is uniform are identified. Analytical expressions for the current–voltage characteristics are obtained. In the context of the developed theory, the possibility of attaining uniform-field conditions in a diode structure with a natural silicon-carbide superlattice is discussed