2017/05/08 by I. Paradisanos, S. Germanis, N. T. Pelekanos +4 · 74 citations
Materials Science · Physics and Astronomy · #2D Materials and Applications #Biexciton #Binding energy #Excitation #Exciton #Monolayer #Organic and Molecular Conductors Research #Photoluminescence #Strong Light-Matter Interactions #Sublinear function #cond-mat.mes-hall
paper · pdf · doi:10.1063/1.4983285
published in Applied Physics Letters 110(19) (American Institute of Physics) · 21 pages, 7 figures
arxiv created 2017/05/08 · openalex publication_date 2017/05/08 · arxiv updated 2017/05/09 · openalex created_date 2017/05/19 · openalex updated_date 2026/08/05
Single layers of WS2 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 WS2 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.