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HL: Fachverband Halbleiterphysik

HL 27: 2D semiconductors and van der Waals heterostructures III (joint session HL/DS)

HL 27.10: Vortrag

Dienstag, 17. März 2020, 12:30–12:45, POT 81

Optoelectronic transport in van der Waals heterostructures of Weyl semimetal MoTe₂ — •Maanwinder Partap Singh^1,2, Jonas Kiemle^1,2, Alexander Holleitner^1,2, and Christoph Kastl^1,2 — ¹Walter Schottky Institut, Technical University of Munich, Am Coulombwall 4, 85748 Garching, Germany — ²Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 Munich, Germany

Unlike topological insulators which are topologically protected by the bulk band gap, Weyl semimetal’s topological protection comes from the fact that their 3D Weyl nodes are separated in momentum space. MoTe₂ belongs to the family of transition metal dichalcogenides, and it crystallizes in several structures. At room temperature, it exists as either hexagonal (2H, a semiconducting phase) or monoclinic (1T’, a metallic phase) structure. Upon cooling, the monoclinic phase undergoes a transition at 240 K into an orthorhombic phase known as T_d phase, which breaks inversion symmetry and results in a type II Weyl semimetal phase. Here, we study the optoelectronic properties of MoTe₂ as function of temperature and layer number using photocurrent and photoconductance spectroscopy. In particular, we investigate the ultrafast electron dynamics using an on-chip Terahertz spectroscopy to disentangle hot electron currents and photogalvanic effects.