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DS: Fachverband Dünne Schichten
DS 11: 2D semiconductors and van der Waals heterostructures II (joint session HL/DS)
DS 11.4: Vortrag
Montag, 16. März 2020, 16:00–16:15, POT 81
Layer-dependent and time-resolved photoluminescence in hBN-encapsulated InSe — •Tommaso Venanzi1,2, Himani Arora1,2, Stephan Winnerl1, Alexej Pashkin1, Phanish Chava1,2, Zahkar Kudrynskyi3, Takashi Tanigushi4, Kenji Watanabe4, Artur Erbe1, Amalia Patane3, Manfred Helm1,2, and Harald Schneider1 — 1Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden, Germany — 2Technische Universität Dresden, 01062 Dresden, Germany — 3School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, UK — 4National Institute for Material Science, 1-1 Namiki, Tsukuba, 305-0044, Japan
In the last years van der Waals semiconductors have become a subject of intense research. Within this class of materials, InSe shows promising optical and electronic properties. Here we present the optical properties of thin flakes of InSe encapsulated in hBN. The encapsulation in hBN protects the InSe flakes from external contamination assuring long-term stability and reducing the disorder potential in the flake. We have studied the photoluminescence (PL) for different temperatures and number of InSe atomic layers. The relative weights of the exciton and electron-hole contributions to the PL emission are discussed using a lineshape analysis. Our model introduces a PL temperature to include the effects of the disorder potential on the PL emission. Furthermore, we observe a sharp increase of the PL lifetime while decreasing the number of layers. This is due to direct-to-indirect bandgap transition driven by the thickness of the InSe flake.