Ring-shaped spatial pattern of exciton luminescence formed due to the hot carrier transport in a locally photoexcited electron-hole bilayer

TL;DR

This paper explains the formation of concentric luminescence rings in a GaAs/AlGaAs quantum well due to hot carrier transport, possibly involving self-organized criticality, supported by numerical simulations matching experimental observations.

Contribution

It introduces a novel explanation for luminescence ring formation involving hot carrier transport and self-organized criticality in semiconductor physics.

Findings

Luminescence rings are caused by hot charge carrier transport at high excitation.

Self-organized criticality may be a key mechanism in carrier transport.

Simulations agree well with experimental luminescence patterns.

Abstract

A consistent explanation of the formation of a ring-shaped pattern of exciton luminescence in GaAs/AlGaAs double quantum wells is suggested. The pattern consists of two concentric rings around the laser excitation spot. It is shown that the luminescence rings appear due to the in-layer transport of hot charge carriers at high photoexcitation intensity. Interestingly, one of two causes of this transport might involve self-organized criticality (SOC) that would be the first case of the SOC observation in semiconductor physics. We test this cause in a many-body numerical model by performing extensive molecular dynamics simulations. The results show good agreement with experiments. Moreover, the simulations have enabled us to identify the particular kinetic processes underlying the formation of each of these two luminescence rings.