Terahertz control of photoluminescence emission in few-layer InSe

TL;DR

This study demonstrates that terahertz pulses can dynamically modulate photoluminescence in few-layer InSe, revealing a reversible quenching mechanism driven by carrier heating and broadening, with implications for opto-electronic device development.

Contribution

It provides the first experimental evidence of terahertz-induced PL control in InSe and elucidates the microscopic mechanism behind PL quenching using microscopic calculations.

Findings

Up to 50% PL quenching observed after terahertz pulse

Reversible PL recovery within 50 ps at 10K

Microscopic calculations confirm carrier heating causes quenching

Abstract

A promising route for the development of opto-elelctronic technology is to use terahertz radiation to modulate the optical properties of semiconductors. Here we demonstrate the dynamical control of photoluminescence (PL) emission in few-layer InSe using picosecond terahertz pulses. We observe a strong PL quenching (up to 50%) after the arrival of the terahertz pulse followed by a reversible recovery of the emission on the time scale of 50ps at T =10K. Microscopic calculations reveal that the origin of the photoluminescence quenching is the terahertz absorption by photo-excited carriers: this leads to a heating of the carriers and a broadening of their distribution, which reduces the probability of bimolecular electron-hole recombination and, therefore, the luminescence. By numerically evaluating the Boltzmann equation, we are able to clarify the individual roles of optical and acoustic phonons in the subsequent cooling process. The same PL quenchingmechanismis expected in other van derWaals semiconductors and the effectwill be particularly strong for materials with low carrier masses and long carrier relaxation time, which is the case for InSe. This work gives a solid background for the development of opto-electronic applications based on InSe, such as THz detectors and optical modulators.