Discrete self-oscillation period branches observed in semiconductor superlattices

Abstract

We investigate the self-sustained current oscillation of a weakly coupled semiconductor superlattice in the dynamical voltage band using a microscopic sequential tunneling model. With the voltage as a control parameter, two types of branches of current oscillation period versus voltage have been observed, which correspond to various oscillation scenarios. The first branch type consists of a series of period branches in accordance with how many charge dipoles need to be created at the emitter side to trigger a dipole-tripole oscillation scenario. For the second branch type, charge dipoles are generated periodically at the emitter, but all of them fail to develop completely and die out, thereby leading to a low-period oscillation scenario without the dipole-tripole process. The bistability between different branches is also observed by voltage up-sweeping and down-sweeping.

Dependence of electron dynamics on magnetic fields in semiconductor superlattices

“…Presently the following directions stand out: SLs with lower dimensions, [15] generation of THz signals, [16] self-sustained current oscillations (SSCOs), and nonlinear dynamics. [17][18][19][20] These interesting physical phenomena are associated with the formation of energy "minibands", which enable electrons to perform Bloch oscillations when a sufficiently high static field is applied along the SL axis. Also, the Bloch oscillations have received much attention for the potential to yield THz generation.…”