Gate-tunable trion switch for excitonic device applications
| Autor: | Nithin Abraham, Kausik Majumdar, Sarthak Das, Sangeeth Kallatt |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Band gap Exciton Physics::Optics FOS: Physical sciences 02 engineering and technology Applied Physics (physics.app-ph) 01 natural sciences law.invention Condensed Matter::Materials Science law 0103 physical sciences Monolayer Mesoscale and Nanoscale Physics (cond-mat.mes-hall) 010306 general physics Photocurrent Condensed Matter - Mesoscale and Nanoscale Physics business.industry Graphene Condensed Matter::Other Heterojunction Physics - Applied Physics 021001 nanoscience & nanotechnology Condensed Matter::Mesoscopic Systems and Quantum Hall Effect Optoelectronics Trion 0210 nano-technology business Excitation |
| Zdroj: | Das, S, Kallatt, S, Abraham, N & Majumdar, K 2020, ' Gate-tunable trion switch for excitonic device applications ', Physical Review B, vol. 101, no. 8, 081413 . https://doi.org/10.1103/PhysRevB.101.081413 |
| DOI: | 10.48550/arxiv.2003.10108 |
| Popis: | Trions are excitonic species with a positive or negative charge, and thus, unlike neutral excitons, the flow of trions can generate a net detectable charge current. Trions under favorable doping conditions can be created in a coherent manner using resonant excitation. In this work, we exploit these properties to demonstrate a gate controlled trion switch in a few-layer graphene/monolayer ${\mathrm{WS}}_{2}$/monolayer graphene vertical heterojunction. By using a high-resolution spectral scan through a temperature controlled variation of the band gap of the ${\mathrm{WS}}_{2}$ sandwich layer, we obtain a gate voltage dependent vertical photocurrent strongly relying on the spectral position of the excitation, and the photocurrent maximizes when the excitation energy is resonant with the trion peak position. Further, the resonant photocurrent thus generated can be effectively controlled by a back gate voltage applied through the incomplete screening of the bottom monolayer graphene, and the photocurrent strongly correlates with the gate dependent trion intensity, while the nonresonant photocurrent exhibits only a weak gate dependence---unambiguously proving a trion driven photocurrent generation under resonance. We estimate a sub-100 fs switching time of the device. The findings are useful towards demonstration of ultrafast excitonic devices in layered materials. |
| Databáze: | OpenAIRE |
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