Electrically tunable GHz oscillations in doped GaAs-AlAs superlattices

TL;DR

This paper reports the experimental realization of tunable GHz oscillations in doped GaAs-AlAs superlattices, analyzing their origin through modeling and identifying different oscillatory modes influenced by device parameters.

Contribution

It introduces a new type of tunable GHz oscillator based on semiconductor superlattices, supported by experimental and theoretical analysis of domain dynamics.

Findings

Demonstrated GHz frequency tunability from 5 to 300 K

Identified three distinct oscillatory modes influenced by device parameters

Predicted a new tunable GHz oscillator based on superlattice domain dynamics

Abstract

Tunable oscillatory modes of electric-field domains in doped semiconductor superlattices are reported. The experimental investigations demonstrate the realization of tunable, GHz frequencies in GaAs-AlAs superlattices covering the temperature region from 5 to 300 K. The orgin of the tunable oscillatory modes is determined using an analytical and a numerical modeling of the dynamics of domain formation. Three different oscillatory modes are found. Their presence depends on the actual shape of the drift velocity curve, the doping density, the boundary condition, and the length of the superlattice. For most bias regions, the self-sustained oscillations are due to the formation, motion, and recycling of the domain boundary inside the superlattice. For some biases, the strengths of the low and high field domain change periodically in time with the domain boundary being pinned within a few quantum wells. The dependency of the frequency on the coupling leads to the prediction of a new type of tunable GHz oscillator based on semiconductor superlattices.