CUED Publications database

Room temperature observation of biexcitons in exfoliated WS<inf>2</inf> monolayers

Paradisanos, I and Germanis, S and Pelekanos, NT and Fotakis, C and Kymakis, E and Kioseoglou, G and Stratakis, E (2017) Room temperature observation of biexcitons in exfoliated WS<inf>2</inf> monolayers. Applied Physics Letters, 110. ISSN 0003-6951

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Single layers of WS are direct gap semiconductors with high photoluminescence (PL) yield holding great promise for emerging applications in optoelectronics. The spatial confinement in a two-dimensional monolayer together with the weak dielectric screening leads to huge binding energies for the neutral excitons as well as other excitonic complexes, such as trions and biexcitons whose binding energies scale accordingly. Here, we report on the existence of biexcitons in mechanically exfoliated WS flakes from 78 K up to room temperature. Performing temperature and power dependent PL measurements, we identify the biexciton emission channel through the superlinear behavior of the integrated PL intensity as a function of the excitation power density. On the contrary, neutral and charged excitons show a linear to sublinear dependence in the whole temperature range. From the energy difference between the emission channels of the biexciton and neutral exciton, a biexciton binding energy of 65-70 meV is determined. 2 2

Item Type: Article
Divisions: Div B > Solid State Electronics and Nanoscale Science
Depositing User: Cron Job
Date Deposited: 14 Mar 2019 01:49
Last Modified: 08 Apr 2021 07:34
DOI: 10.1063/1.4983285