Nonlinear Charge Transport and Excitable Phenomena in Semiconductor Superlattices

Area of Science:

• Condensed Matter Physics
• Quantum Mechanics
• Nanotechnology

Background:

• Semiconductor superlattices are nanostructures with repeating quantum wells and barriers.
• Electron transport is primarily sequential resonant tunneling for thick barriers.

Purpose of the Study:

• Review quantum transport in semiconductor superlattices.
• Explore phenomena like charge density waves, current oscillations, and resonance effects.
• Highlight device applications based on these properties.

Main Methods:

• Analysis of rate equations for electron densities, currents, and electric potential.
• Investigation of superlattice behavior under varying parameters (configuration, doping, temperature, bias).
• Examination of phenomena such as coherence resonance and stochastic resonance.

Main Results:

• Superlattices can exhibit excitable system behavior with large transients.
• Self-sustained current oscillations (periodic, quasiperiodic, chaotic) arise from charge density waves.
• Coherence and stochastic resonance phenomena are observed and controllable.

Conclusions:

• Superlattice dynamics are tunable, allowing for robust chaos and controlled oscillations.
• Coherence and stochastic resonance can be utilized for weak signal detection.
• Fast random sequence generators can be developed for secure communications.