Large Enhancement of the Photoluminescence Emission of Photoexcited Undoped GaAs Quantum Wells Induced by an Intense Single-Cycle Terahertz Pulse

TL;DR

This study demonstrates that intense single-cycle terahertz pulses can dramatically enhance photoluminescence in undoped GaAs quantum wells by ionizing impurity states and releasing carriers, leading to a 10,000-fold increase in exciton population.

Contribution

It reveals a novel method of boosting photoluminescence in quantum wells using intense THz pulses to ionize impurity states and release carriers, a process not previously demonstrated.

Findings

Photoluminescence flash increases 10,000-fold under THz pulses.

THz electric field ionizes impurity states during a picosecond.

Carrier release from impurity reservoirs enhances exciton population.

Abstract

Intense terahetz (THz) pulses induce a photoluminescence (PL) flash from undoped high-quality GaAs/AlGaAs quantum wells under continuous wave laser excitation. The number of excitons increases 10000-fold from that of the steady state under only laser excitation. The THz electric field dependence and the relaxation dynamics of the PL flash intensity suggest that the strong electric field of the THz pulse ionizes impurity states during the one-picosecond period of the THz pulse and release carriers from a giant reservoir containing impurity states in the AlGaAs layers.