13 research outputs found
The physics of space charge instabilities and temporal chaos in extrinsic photoconductors
Sequence of different types of nonlinear current oscillation in n-GaAs
Self-generated chaotic current fluctuations in the post-breakdown regime of a n-GaAs layer at 4.2 K have been analyzed in detail. Without an external magnetic field only regular oscillations were observed. Increasing the magnetic field strength up to 100 mT generates a sequence of quasiperiodic and frequency-locking current oscillations and finally a Ruelle-Takens-Newhouse scenario with chaos. This may be understood by assuming two coupled oscillatory processes caused by dielectric relaxation and energy relaxation in the distribution of free carriers
Intermittent breakdown of current-oscillation tori in n-type GaAs epitaxial layers
Self-sustained current oscillations in high-purity n-type GaAs epitaxial layers were investigated for intermittent behavior in the control parameter plane constituted by the constant bias voltage and an external magnetic field. Intermittent windows were observed in a sequence of Hopf bifurcations. Quasiperiodic and frequency-locked oscillations were found to follow an intermittency type-II or type-III route to chaos in the Pomeau-Manneville classification scheme. Additionally, intermittent bursts due to noise were observed at voltages well below the threshold of bifurcation
A negative differential conductivity due to recombination and impact ionization in semiconductors at low temperatures
A simple morphogenetic reaction-diffusion model describing nonlinear transport phenomena in semiconductors
Classification of current instabilities during low-temperature breakdown in germanium
We present experimental investigations on the spatio-temporal nonlinear current flow in the post-breakdown regime of p-germanium at liquid-helium temperatures. The basic nonlinear effects are characterized in terms of the underlying semiconductor physics, taking into account the influence of different experimental parameters