Effective detection of spatio-temporal carrier dynamics by carrier capture

R Rosati,T Kuhn,D E Reiter,F Lengers

doi:10.1088/1361-648x/ab17a8

Abstract

The spatio-temporal dynamics of electrons moving in a 2D plane is challenging to detect when the required resolution shrinks simultaneously to nanometer length and subpicosecond time scale. We propose a detection scheme relying on phonon-induced carrier capture from 2D unbound states into the bound states of an embedded quantum dot. This capture process happens locally and here we explore if this locality is sufficient to use the carrier capture process as detection of the ultrafast diffraction of electrons from an obstacle in the 2D plane. As an example we consider an electronic wave packet traveling in a semiconducting monolayer of the transition metal dichalcogenide MoSe2, and we study the scattering-induced dynamics using a single particle Lindblad approach. Our results offer a new way to high resolution detection of the spatio-temporal carrier dynamics.

Highlights

Detecting the spatio-temporal dynamics of generic particles [1–11] is challenging when a subpicosecond temporal scale has to be combined with a nanometer spatial resolution [4, 8]
We propose a detection scheme relying on phonon-induced carrier capture from 2D unbound states into the bound states of an embedded quantum dot
This capture process happens locally and here we explore if this locality is sufficient to use the carrier capture process as detection of the ultrafast diffraction of electrons from an obstacle in the 2D plane

Summary

Introduction

Detecting the spatio-temporal dynamics of generic (quasi-) particles [1–11] is challenging when a subpicosecond temporal scale has to be combined with a nanometer spatial resolution [4, 8]. Matter 31 (2019) 28LT01 a class of 2D semiconducting materials which has recently attracted lots of attention [32–38], mostly due to their excitonic properties, a mixture of bound and unbound electron–hole pairs could be present [39, 40] In these mat erials QDs can be created efficiently, e.g. by applying a tensile strain [41–48], resulting in clearly resolved optical signals. When an electronic density travels inside the TMDC monolayer and gets diffracted at such an obstacle, the spatial dynamics can be theoretically calculated exactly in well specified points. We compare this exact quantity with the predictions provided by the proposed carrier-capture detection scheme, which can be experimentally realized. This will give insight in the efficiency of the proposed scheme

Capture-free dynamics

Detection via carrier capture

Conclusions