Spatio-Temporal Dynamics of Filament Formation Induced by Impurity Impact Ionization in GaAs

Abstract

Due to the inherent nonlinearities of the underlying generation-recombination (GR) processes in semiconductors, impact ionization of trapped carriers in high electric fields — often associated with S-shaped negative differential conductivity (SNDC) of the sample — constitutes a physical mechanism that gives rise to a menagerie of spatio-temporal bifurcation scenarios1–3. Self-organized transitions of a spatially homogeneous steady state to a variety of filamentary structures are prominent examples for possible bifurcations. These current filaments have been predicted theoretically1,4–9 and found experimentally10–12 in a variety of semiconductor materials, e.g., p-Ge or n-GaAs, at liquid Helium temperatures. Recently the evolution of such structures starting from a high resistivity state has received increasing interest13,14.