Dresden 2020 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 27: 2D semiconductors and van der Waals heterostructures III (joint session HL/DS)
HL 27.10: Talk
Tuesday, March 17, 2020, 12:30–12:45, POT 81
Optoelectronic transport in van der Waals heterostructures of Weyl semimetal MoTe2 — •Maanwinder Partap Singh1,2, Jonas Kiemle1,2, Alexander Holleitner1,2, and Christoph Kastl1,2 — 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 Td 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.