Effect of temperature on resonant electron transport through stochastic conduction channels in superlattices

TL;DR

This study demonstrates that increasing temperature in semiconductor superlattices enhances resonant electron transport and current oscillations by affecting stochastic web conduction channels, contrary to typical expectations of thermal damping.

Contribution

It reveals how elevated temperatures strengthen resonant peaks and alter electron dynamics in superlattices through interplay with stochastic web channels and self-consistent transport modeling.

Findings

Resonant peaks in drift velocity increase with temperature.

Temperature affects threshold voltage and oscillation frequency.

Self-consistent models show enhanced electron transport at higher temperatures.

Abstract

We show that resonant electron transport in semiconductor superlattices with an applied electric and tilted magnetic field can, surprisingly, become more pronounced as the lattice and conduction electron temperature increases from 4.2 K to room temperature and beyond. It has previously been demonstrated that at certain critical field parameters, the semiclassical trajectories of electrons in the lowest miniband of the superlattice change abruptly from fully localised to completely unbounded. The unbounded electron orbits propagate through intricate web patterns, known as stochastic webs, in phase space, which act as conduction channels for the electrons and produce a series of resonant peaks in the electron drift velocity versus electric field curves. Here, we show that increasing the lattice temperature strengthens these resonant peaks due to a subtle interplay between thermal population of the conduction channels and transport along them. This enhances both the electron drift velocity and the influence of the stochastic webs on the current-voltage characteristics, which we calculate by making self-consistent solutions of the coupled electron transport and Poisson equations throughout the superlattice. These solutions reveal that increasing the temperature also transforms the collective electron dynamics by changing both the threshold voltage required for the onset of self-sustained current oscillations, produced by propagating charge domains, and the oscillation frequency.