Exciton diffusion in monolayer semiconductors with suppressed disorder
Artikel i vetenskaplig tidskrift, 2020

Tightly bound excitons in monolayer semiconductors represent a versatile platform to study two-dimensional propagation of neutral quasiparticles. Their intrinsic properties, however, can be severely obscured by spatial energy fluctuations due to a high sensitivity to the immediate environment. Here, we take advantage of the encapsulation of individual layers in hexagonal boron nitride to strongly suppress environmental disorder. Diffusion of excitons is then directly monitored using time and spatially resolved emission microscopy at ambient conditions. We consistently find very efficient propagation with linear diffusion coefficients up to 10 cm(2)/s, corresponding to room-temperature effective mobilities as high as 400 cm(2)/Vs as well as a correlation between rapid diffusion and short population lifetime. At elevated densities we detect distinct signatures of many-particle interactions and consequences of strongly suppressed Auger-type exciton-exciton annihilation. A combination of analytical and numerical theoretical approaches is employed to provide pathways toward comprehensive understanding of the observed linear and nonlinear propagation phenomena. We emphasize the role of dark exciton states and present a mechanism for diffusion facilitated by free-electron hole plasma from entropy-ionized excitons.

Författare

Jonas Zipfel

Universität Regensburg

Marvin Kulig

Universität Regensburg

Raul Perea Causin

Kondenserad materie- och materialteori

Samuel Brem

Kondenserad materie- och materialteori

Jonas D. Ziegler

Universität Regensburg

Roberto Rosati

Kondenserad materie- och materialteori

Takashi Taniguchi

National Institute for Materials Science (NIMS)

Kenji Watanabe

National Institute for Materials Science (NIMS)

Mikhail M. Glazov

Ioffe Phys Tech Inst

Ermin Malic

Kondenserad materie- och materialteori

Alexey Chernikov

Universität Regensburg

PHYSICAL REVIEW B

2469-9950 (ISSN) 2469-9969 (eISSN)

Vol. 101 11 115430

Ämneskategorier

Atom- och molekylfysik och optik

Annan fysik

Den kondenserade materiens fysik

DOI

10.1103/PhysRevB.101.115430

Mer information

Senast uppdaterat

2020-05-20