Interplay of the exciton and electron-hole plasma recombination on the photoluminescence dynamics in bulk GaAs

TL;DR

This study investigates how exciton and electron-hole plasma recombination influence photoluminescence in bulk GaAs across different temperatures and excitation densities, revealing how carrier dynamics signal the metal-insulator transition.

Contribution

It provides a detailed analysis of the interplay between exciton and plasma recombination and how this affects photoluminescence, highlighting the carrier dynamics as indicators of phase transitions.

Findings

Carrier dynamics can directly monitor the metal-insulator transition.

Photoluminescence rise time dependence changes around 49 K.

Rise-time dependence on temperature shifts at high excitation densities.

Abstract

We present a systematic study of the exciton/electron-hole plasma photoluminescence dynamics in bulk GaAs for various lattice temperatures and excitation densities. The competition between the exciton and electron-hole pair recombination dominates the onset of the luminescence. We show that the metal-to-insulator transition, induced by temperature and/or excitation density, can be directly monitored by the carrier dynamics and the time-resolved spectral characteristics of the light emission. The dependence on carrier density of the photoluminescence rise time is strongly modified around a lattice temperature of 49 K, corresponding to the exciton binding energy (4.2 meV). In a similar way, the rise-time dependence on lattice temperature undergoes a relatively abrupt change at an excitation density of 120-180x10^15 cm^-3, which is about five times greater than the calculated Mott density in GaAs taking into account many body corrections.