Excitons, trions and Rydberg states in monolayer MoS_2 revealed by low-temperature photocurrent spectroscopy
Exciton physics in two-dimensional semiconductors are typically studied by photoluminescence spectroscopy. However, this technique does not allow for direct observation of non-radiating excitonic transitions. Here, we use low-temperature photocurrent spectroscopy as an alternative technique to inves...
| Autores: | , , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2020 |
| País: | España |
| Institución: | Universidad Complutense de Madrid (UCM) |
| Repositorio: | Docta Complutense |
| Idioma: | inglés |
| OAI Identifier: | oai:docta.ucm.es:20.500.14352/7552 |
| Acceso en línea: | https://hdl.handle.net/20.500.14352/7552 |
| Access Level: | acceso abierto |
| Palabra clave: | 538.9 Photoluminescence Physics Multidisciplinary Física de materiales Física del estado sólido 2211 Física del Estado Sólido |
| Sumario: | Exciton physics in two-dimensional semiconductors are typically studied by photoluminescence spectroscopy. However, this technique does not allow for direct observation of non-radiating excitonic transitions. Here, we use low-temperature photocurrent spectroscopy as an alternative technique to investigate excitonic transitions in a high-quality monolayer MoS_2 phototransistor. The resulting spectra presents excitonic peaks with linewidths as low as 8 meV. We identify spectral features corresponding to the ground states of neutral excitons (X^A_(1s) and X^B_(1s) and charged trions (T^A and T^B) as well as up to eight additional spectral lines at energies above the X^B_(1s) transition, which we attribute to the Rydberg series of excited states of X^A and X^B. The intensities of the spectral features can be tuned by the gate and drain-source voltages. Using an effective-mass theory for excitons in two-dimensional systems we are able to accurately fit the measured spectral lines and unambiguously associate them with their corresponding Rydberg states. |
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