Observation of the exciton Mott transition in the photoluminescence of coupled quantum wells

TL;DR

This study observes the exciton Mott transition in coupled quantum wells, demonstrating a gradual phase change from insulating to conducting states as a function of carrier density and temperature, with electric field tuning.

Contribution

First experimental observation of the gradual exciton Mott transition in coupled quantum wells using photoluminescence measurements and electric field control.

Findings

Transition occurs around 2×10^{10} cm^{-2} carrier density.

Transition temperature range is 12-16 K.

Electric field influences the transition dynamics via the Stark effect.

Abstract

Indirect excitons in coupled quantum wells have long radiative lifetimes and form a cold quasi-two-dimensional population suitable for studying collective quantum effects. Here we report the observation of the exciton Mott transition from an insulating (excitons) to a conducting (ionized electron-hole pairs) phase, which occurs gradually as a function of carrier density and temperature. The transition is inferred from spectral and time-resolved photoluminescence measurements around a carrier density of $2\times10^{10} \mathrm{cm}^{-2}$ and temperatures of $12-16 \mathrm{K}$. An externally applied electric field is employed to tune the dynamics of the transition via the quantum-confined Stark effect. Our results provide evidence of a gradual nature of the exciton Mott transition.