激子
振荡器强度
单层
光致发光
材料科学
半导体
光谱学
薄膜
共振(粒子物理)
谱线
凝聚态物理
分子物理学
原子物理学
化学
光电子学
纳米技术
物理
量子力学
天文
作者
Ashish Arora,Maciej Koperski,K. Nogajewski,J. Marcus,C. Faugeras,M. Potemski
出处
期刊:Nanoscale
[The Royal Society of Chemistry]
日期:2015-01-01
卷期号:7 (23): 10421-10429
被引量:264
摘要
We present optical spectroscopy (photoluminescence and reflectance) studies of thin layers of the transition metal dichalcogenide WSe2, with thickness ranging from mono- to tetra-layer and in the bulk limit. The investigated spectra show the evolution of excitonic resonances as a function of layer thickness, due to changes in the band structure and, importantly, due to modifications of the strength of Coulomb interactions as well. The observed temperature-activated energy shift and broadening of the fundamental direct exciton are well accounted for by standard formalisms used for conventional semiconductors. A large increase of the photoluminescence yield with temperature is observed in a WSe2 monolayer, indicating the existence of competing radiative channels. The observation of absorption-type resonances due to both neutral and charged excitons in the WSe2 monolayer is reported and the effect of the transfer of oscillator strength from charged to neutral excitons upon an increase of temperature is demonstrated.
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