Spatiotemporal dynamics of excitons in monolayer and bulk WS2

被引：73

作者：

He, Jiaqi ^{[1
,2
]}

He, Dawei ^{[1
]}

Wang, Yongsheng ^{[1
]}

Cui, Qiannan ^{[2
]}

Ceballos, Frank ^{[2
]}

Zhao, Hui ^{[2
]}

机构：

[1] Beijing Jiaotong Univ, Inst Optoelect Technol, Minist Educ, Key Lab Luminescence & Opt Informat, Beijing 100044, Peoples R China

[2] Univ Kansas, Dept Phys & Astron, Lawrence, KS 66045 USA

来源：

NANOSCALE | 2015年 / 7卷 / 21期

基金：

美国国家科学基金会;

关键词：

FEW-LAYER MOS2; SINGLE-LAYER; EXFOLIATION; MONO; FABRICATION; TRANSISTORS; DISULFIDE; TRANSPORT; GROWTH; SCALE;

D O I：

10.1039/c5nr00188a

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

Spatiotemporal dynamics of excitons in monolayer and bulk WS2 at room temperature is studied by transient absorption microscopy in the reflection geometry. Excitons are formed from photocarriers injected by a tightly focused 390 nm pump pulse, and monitored by detecting different reflection of a time-delayed and spatially scanned 620 nm probe pulse. We obtain exciton lifetimes of 22 +/- 1 and 110 +/- 10 ps in monolayer and bulk WS2, respectively. Both lifetimes are independent of the exciton density, showing the absence of multi-exciton recombination processes. Exciton diffusion coefficients of 60 +/- 20 and 3.5 +/- 0.5 cm(2) s(-1) are obtained in monolayer and bulk samples, respectively. These results provide a foundation for understanding excitons in this new material and its optoelectronic applications.

引用

页码：9526 / 9531

页数：6

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