Non-linear dynamics of semiconductor superlattices

Abstract

In the last decade, non-linear dynamical transport in semiconductor superlattices (SLs) has witnessed significant progress in theoretical descriptions as well as in experimentally observed non-linear phenomena. However, until now, a clear distinction between non-linear transport in strongly and weakly coupled SLs was missing, although it is necessary to provide a detailed description of the observed phenomena. In this review, strongly coupled SLs are described by spatially continuous equations and display self-sustained current oscillations due to the periodic motion of a charge dipole as in the Gunn effect for bulk semiconductors. In contrast, weakly coupled SLs have to be described by spatially discrete equations. Therefore, weakly coupled SLs exhibit a more complex dynamical behaviour than strongly coupled ones, which includes the formation of stationary electric field domains, pinning or propagation of domain walls consisting of a charge monopole, switching between stationary domains, self-sustained current oscillations due to the recycling motion of a charge monopole and chaos. This review summarizes the existing theories and the experimentally observed non-linear phenomena for both types of semiconductor SLs.

Four-Wave Semidiscrete Nonlinear Integrable System with 𝒫𝒯-Symmetry

“…Among the most typical physical objects, where the semidiscrete nonlinear systems find their applications are the semiconductor superlattices [10,26,34,51], electric superstructures [29], optical waveguide arrays [15], photonic crystal fibers [7] as well as the regular macromolecular structures of both natural [16] and synthetic [31] origin. The extensive bibliography on experimental realizations of discrete soliton-like entities is presented, e.g.…”

Two miniband model for self-sustained oscillations of the current through resonant-tunneling semiconductor superlattices

“…For small voltage values, electron transport chiefly involves the lowest miniband and there are many appropriate kinetic theory descriptions: semiclassical Boltzmann-type equations [1][2][3][4][5] , density matrix formulations 6,7 , transport equations for the nonequilibrium Green function (NGF) 8 , and Wigner-Poisson (WP) equations 9 . Semiclassical equations are easier to handle and, in particular, can be used to describe space-charge instabilities such as self-sustained oscillations of the current (SSOC) in dc voltage biased SLs due to the formation and dynamics of electric field domains 10 . SSOC can be found by deriving and solving a drift-diffusion system from the semiclassical kinetic equation 5 , or by a direct numerical solution of the latter 11 .…”

Noise temperature spectrum of hot electrons in semiconductor superlattices

“…10 Recently, nonlinear dynamics involving electron transport in semiconductor superlattice driven by an intense terahertz electromagnetic irradiation has been a central focus of theoretical and experimental studies. [11][12][13][14][15][16][17][18] Keay et al 13 observed the photon-assisted tunneling and oscillatory dependence of the photon induced currents on terahertz electric field. It was reported that current through a biased GaAs/ AlAs superlattice is reduced when exposed to an intense terahertz field.…”