Influence of direct deposition of dielectric materials on the optical response of monolayer WS$_2$
| Autor: | Tinghe Yun, Elena A. Ostrovskaya, C. Notthoff, Michael S. Fuhrer, Andrew G. Truscott, Semonti Bhattacharyya, Patrick Kluth, Qingdong Ou, Eliezer Estrecho, Chung Kim Nguyen, Matthias Wurdack, Maciej Pieczarka, Torben Daeneke |
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| Rok vydání: | 2021 |
| Předmět: |
Condensed Matter - Materials Science
Materials science Photoluminescence Physics and Astronomy (miscellaneous) business.industry Materials Science (cond-mat.mtrl-sci) FOS: Physical sciences Dielectric Chemical vapor deposition Physics - Applied Physics Applied Physics (physics.app-ph) Sputter deposition Electron beam physical vapor deposition Atomic layer deposition Condensed Matter::Materials Science Plasma-enhanced chemical vapor deposition Monolayer Optoelectronics business |
| DOI: | 10.48550/arxiv.2104.09893 |
| Popis: | We investigate the effects of direct deposition of different dielectric materials (AlOx, SiOx, SiNx) onto atomically thin TMDC WS2 on its optical response using atomic layer deposition (ALD), electron beam evaporation (EBE), plasma-enhanced chemical vapor deposition (PECVD), and magnetron sputtering. The photoluminescence measurements reveal quenching of the excitonic emission after all deposition processes, which is linked to the increased level of charge doping and associated rise of the trion emission and/or the localized (bound) exciton emission. Furthermore, Raman spectroscopy allows us to clearly correlate the observed changes in excitonic emission with the increased levels of lattice disorder and defects. In particular, we show that the different doping levels in a monolayer WS2 capped by a dielectric material are strongly related to the defects in the WS2 crystal introduced by all capping methods, except for ALD. The strong charge doping in the ALD-capped sample seems to be caused by other factors, such as deviations in the dielectric layer stoichiometry or chemical reactions on the monolayer surface, which makes ALD distinct from all other techniques. Overall, the EBE process results in the lowest level of doping and defect densities and in the largest spectral weight of the exciton emission in the PL. Sputtering is revealed as the most aggressive dielectric capping method for WS2, fully quenching its optical response. Our results demonstrate and quantify the effects of direct deposition of dielectric materials onto monolayer WS2, which can provide valuable guidance for the efforts to integrate monolayer TMDCs into functional optoelectronic devices. |
| Databáze: | OpenAIRE |
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