Femtosecond cooling of hot electrons in CdSe quantum-well platelets
| Autor: | Sippel, Philipp, Albrecht, Wiebke, van der Bok, Johanna C., Moes, Relinde, Hannappel, Thomas, Eichberger, Rainer, Vanmaekelbergh, Daniel, Sub Soft Condensed Matter, Sub Condensed Matter and Interfaces, Condensed Matter and Interfaces |
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| Přispěvatelé: | Sub Soft Condensed Matter, Sub Condensed Matter and Interfaces, Condensed Matter and Interfaces |
| Rok vydání: | 2015 |
| Předmět: |
Materials science
Phonon Orders of magnitude (temperature) Photoemission spectroscopy TR-2PPE quantum well Physics::Optics Bioengineering RELAXATION DYNAMICS CdSe law.invention Condensed Matter::Materials Science POLAR SEMICONDUCTORS law hot electron relaxation General Materials Science SEMICONDUCTOR NANOCRYSTALS Quantum well platelet DOTS Phonon scattering PHONON-SCATTERING business.industry Mechanical Engineering GAAS ENERGY RELAXATION General Chemistry Condensed Matter Physics CARRIERS OPTICAL PHONONS Femtosecond Optoelectronics COLLOIDAL NANOPLATELETS business Excitation photoemission Electron cooling |
| Zdroj: | Nano Letters, 15(4), 2409. American Chemical Society |
| ISSN: | 1530-6992 1530-6984 |
| Popis: | Semiconductor quantum wells are ubiquitous in high-performance optoelectronic devices such as solar cells and lasers. Understanding and controlling of the (hot) carrier dynamics is essential to optimize their performance. Here, we study hot electron cooling in colloidal CdSe quantum-well nanoplatelets using ultrafast two-photon photoemission spectroscopy at low excitation intensities, resulting typically in 1-5 hot electrons per platelet. We observe initial electron cooling in the femtosecond time domain that slows down with decreasing electron energy and is finished within 2 ps. The cooling is considerably faster at cryogenic temperatures than at room temperature, and at least for the systems that we studied, independent of the thickness of the platelets (here 3-5 CdSe units) and the presence of a CdS shell. The cooling rates that we observe are orders of magnitude faster than reported for similar CdSe platelets under strong excitation. Our results are understood by a classic cooling mechanism with emission of longitudinal optical phonons without a significant influence of the surface. |
| Databáze: | OpenAIRE |
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