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| Autori principali: | , , , , , , |
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| Natura: | Preprint |
| Pubblicazione: |
2025
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| Accesso online: | https://arxiv.org/abs/2505.14056 |
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| _version_ | 1866910956927320064 |
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| author | Tchuimeni, Daniel O. Siebadji Ziegler, Marc Crégut, Olivier Gilliot, Pierre Morhain, Christian Balocchi, Andrea Gallart, Mathieu |
| author_facet | Tchuimeni, Daniel O. Siebadji Ziegler, Marc Crégut, Olivier Gilliot, Pierre Morhain, Christian Balocchi, Andrea Gallart, Mathieu |
| contents | We investigate the ultrafast dynamics of excitons in a 2.6 nm-thick $\mathrm{ZnO/Zn_{0.84}Mg_{0.16}O}$ quantum well grown on a c-axis sapphire substrate, using non-degenerate time-resolved pump-probe spectroscopy. A pump pulse at 266 nm generates photocarriers within the ZnMgO barriers, and their dynamics is monitored through time-resolved differential reflectance measurements using a supercontinuum probe spanning the 345-400 nm spectral range. Photocarriers generated in the barriers rapidly relax into the quantum well, where they form excitons within sub-picosecond timescales. These excitons quickly thermalize and become localized, likely due to interface disorder or well-width fluctuations, as supported by photoluminescence measurements showing a clear Stokes shift and the absence of free exciton emission. A phonon-assisted absorption process, leading to the effective thermalization of excitons, is observed and analyzed. We identify moreover a negative differential reflectance feature as a photoinduced absorption into a biexciton state, with a binding energy ranging from 18 to 22 meV depending on temperature. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_14056 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Carrier Thermalization and Biexciton Formation in a Polar ZnO/Zn$_{0.84}$Mg$_{0.16}$O Quantum Well Probed by Ultrafast Broadband Spectroscopy Tchuimeni, Daniel O. Siebadji Ziegler, Marc Crégut, Olivier Gilliot, Pierre Morhain, Christian Balocchi, Andrea Gallart, Mathieu Mesoscale and Nanoscale Physics Optics We investigate the ultrafast dynamics of excitons in a 2.6 nm-thick $\mathrm{ZnO/Zn_{0.84}Mg_{0.16}O}$ quantum well grown on a c-axis sapphire substrate, using non-degenerate time-resolved pump-probe spectroscopy. A pump pulse at 266 nm generates photocarriers within the ZnMgO barriers, and their dynamics is monitored through time-resolved differential reflectance measurements using a supercontinuum probe spanning the 345-400 nm spectral range. Photocarriers generated in the barriers rapidly relax into the quantum well, where they form excitons within sub-picosecond timescales. These excitons quickly thermalize and become localized, likely due to interface disorder or well-width fluctuations, as supported by photoluminescence measurements showing a clear Stokes shift and the absence of free exciton emission. A phonon-assisted absorption process, leading to the effective thermalization of excitons, is observed and analyzed. We identify moreover a negative differential reflectance feature as a photoinduced absorption into a biexciton state, with a binding energy ranging from 18 to 22 meV depending on temperature. |
| title | Carrier Thermalization and Biexciton Formation in a Polar ZnO/Zn$_{0.84}$Mg$_{0.16}$O Quantum Well Probed by Ultrafast Broadband Spectroscopy |
| topic | Mesoscale and Nanoscale Physics Optics |
| url | https://arxiv.org/abs/2505.14056 |