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HL: Fachverband Halbleiterphysik

HL 20: 2D semiconductors and van der Waals heterostructures II (joint session HL/DS)

HL 20.4: Vortrag

Montag, 16. März 2020, 16:00–16:15, POT 81

Layer-dependent and time-resolved photoluminescence in hBN-encapsulated InSe — •Tommaso Venanzi^1,2, Himani Arora^1,2, Stephan Winnerl¹, Alexej Pashkin¹, Phanish Chava^1,2, Zahkar Kudrynskyi³, Takashi Tanigushi⁴, Kenji Watanabe⁴, Artur Erbe¹, Amalia Patane³, Manfred Helm^1,2, 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.