Inhomogeneous photocarrier dynamics and transport in monolayer MoS2 by ultrafast microscopy.
Nanotechnology
; 30(48): 485701, 2019 11 29.
Article
em En
| MEDLINE
| ID: mdl-31437820
ABSTRACT
Monolayer MoS2 as a member of two-dimensional transition metal dichalcogenides (TMDs) has attracted considerable attention due to its superior optoelectronic properties. Understanding the photocarrier dynamics and transport in these two dimensional systems is beneficial for applications from photovoltaics to sensing. However, various structural defects strongly impact the dynamics and transport of photocarriers. Especially there lacks a precise measuring and understanding of photocarrier transport in TMDs. Here, femtosecond transient absorption spectroscopy and microscopy were employed to study the photocarrier dynamics and transport in monolayer MoS2. Defect correlated photocarrier dynamics are observed across the monolayer MoS2 where exciton formation and nonradiative recombination are the two dominant decay processes. To the best of our knowledge, we report two distinct photocarrier transport regimes in MoS2 for the first time with diffusion coefficients of [Formula see text] cm2 s-1 and [Formula see text] cm2 s-1, by taking advantages of ultrafast microscopy with â¼20 nm spatial precision and â¼200 fs temporal resolution. These two regimes are ascribed to fast hot photocarrier diffusion and slow phonon-limited thermal diffusion, respectively. The results indicate that the initial fast photocarrier transport is less dependent on structural defects compared to photocarrier relaxation dynamics which may be useful for hot photocarrier extraction applications.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article