Observation of Ultrafast Free Carrier Dynamics in Single Layer MoS2

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• 作者：Antonija Grubi拧i膰 膶abo ; Jill A. Miwa ; Signe S. Gr酶nborg ; Jonathon M. Riley ; Jens C. Johannsen ; Cephise Cacho ; Oliver Alexander ; Richard T. Chapman ; Emma Springate ; Marco Grioni ; Jeppe V. Lauritsen ; Phil D. C. King ; Philip Hofmann ; S酶ren Ulstrup
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：September 9, 2015
• 年：2015
• 卷：15
• 期：9
• 页码：5883-5887
• 全文大小：475K
• ISSN：1530-6992

文摘

The dynamics of excited electrons and holes in single layer (SL) MoS₂ have so far been difficult to disentangle from the excitons that dominate the optical response of this material. Here, we use time- and angle-resolved photoemission spectroscopy for a SL of MoS₂ on a metallic substrate to directly measure the excited free carriers. This allows us to ascertain a direct quasiparticle band gap of 1.95 eV and determine an ultrafast (50 fs) extraction of excited free carriers via the metal in contact with the SL MoS₂. This process is of key importance for optoelectronic applications that rely on separated free carriers rather than excitons.