Photo-Excited Semiconductor Superlattices as Constrained Excitable Media: Motion of Dipole Domains and Current Self-Oscillations Articles uri icon

publication date

  • March 2010

start page

  • 35322

issue

  • 3

volume

  • 81

international standard serial number (ISSN)

  • 1098-0121

electronic international standard serial number (EISSN)

  • 1538-4489

abstract

  • A model for charge transport in undoped photoexcited semiconductor superlattices, which includes the dependence of the electron-hole recombination on the electric field and on the photoexcitation intensity
    through the field-dependent recombination coefficient, is proposed and
    analyzed. Under dc voltage bias and high photoexcitation intensities,
    there appear self-sustained oscillations of the current due to a
    repeated homogeneous nucleation of a number of charge dipole waves
    inside the superlattice. In contrast to the case of a constant
    recombination coefficient, nucleated dipole waves can split for a
    field-dependent recombination coefficient in two oppositely moving
    dipoles. The key for understanding these unusual properties is that
    these superlattices have a unique static electric-field domain. At the
    same time, their dynamical behavior is akin to the one of an extended
    excitable system: an appropriate finite disturbance of the unique stable
    fixed point may cause a large excursion in phase space before returning
    to the stable state and trigger pulses and wave trains. The voltage
    bias constraint causes new waves to be nucleated when old ones reach the
    contact.