Scalable van der Waals heterostacks for optoelectronics

In this talk recent advances on the synthesis and applications of large-scale highly-crystalline 2D van der Waals heterostacks will be presented. The electronic performance of single-crystal graphene arrays obtained via patterned growth [1] will be discussed in terms of homogeneity and repeatability. Particular focus will be put in the heterostack obtained by directly synthetizing via chemical vapor deposition (CVD) tungsten disulfide (WS2) on graphene [2]. It will be shown via microstructural and electronic characterization that WS2 aligns on top of graphene with a 0° orientation, the interface is atomically sharp and the spin-orbit splitting of monolayer WS2 on graphene is the largest reported to date [3]. In virtue of its band alignment and remarkable spin-orbit splitting, this system gains strong appeal for optoelectronics and optospintronic applications. It will be presented an entirely scalable hybrid WS2/graphene photodetector with a photoresponsivity of about 100 A/W. [1] V. Miseikis, F. Bianco, J David, M. Gemmi, V. Pellegirni, M. Romagnoli, C. Coletti, 2D Materials 4 (2), 021004, 2017. [2] A. Rossi, H. Buech, C. Di Rienzo, V. Miseikis, D. Convertino, A. Al-Temimy, V. Voliani, M. Gemmi, V. Piazza, C. Coletti, 2D Materials 3 (3), 031013, 2016. [3] S. Forti, A. Rossi, H. Büch, T. Cavallucci, F. Bisio, A. Sala, T.O. Mentes, A. Locatelli, M. Magnozzi, M. Canepa, K. Müller, S. Link, U. Starke, V. Tozzini, C. Coletti, Nanoscale 9 (42), 16412-16419 (2017).