Transient absorption of transition metal dichalcogenide monolayers studied by a photodope-pump-probe technique
| Autor: | Peymon Zereshki, Mohammad Mahdi Tavakoli, Jihoon Park, Pavel Valencia-Acuna, Jing Kong, Hui Zhao |
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| Rok vydání: | 2020 |
| Předmět: |
Photoluminescence
Materials science Exciton 02 engineering and technology Chemical vapor deposition 021001 nanoscience & nanotechnology 01 natural sciences Molecular physics Transition metal dichalcogenide monolayers Reflection (mathematics) 0103 physical sciences Ultrafast laser spectroscopy 010306 general physics 0210 nano-technology Spectroscopy Ultrashort pulse |
| Zdroj: | Physical Review B. 102 |
| ISSN: | 2469-9969 2469-9950 |
| Popis: | We report three-pulse photodope-pump-probe measurements on photocarrier dynamics in semiconducting transition metal dichalcogenide monolayers of ${\mathrm{MoS}}_{2}$, ${\mathrm{WS}}_{2}$, ${\mathrm{MoSe}}_{2}$, and ${\mathrm{WSe}}_{2}$. The samples are fabricated by metal-organic chemical vapor deposition and mechanical exfoliation techniques and characterized by photoluminescence spectroscopy. In the time-resolved measurement, the samples are first photodoped by a prepulse, which injects background photocarriers of various densities. A pump pulse then injects photocarriers, whose dynamics is monitored by measuring a differential reflection of a time-delayed probe pulse. We found that the ultrafast decay component of the differential reflection signal, which has been widely reported before, shows minimal dependence on the background exciton density. This observation shows that a previously suggested carrier-trapping model cannot account for this component. The results thus further support an exciton-formation model that was previously proposed based on spectroscopic evidence. |
| Databáze: | OpenAIRE |
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