Resonant tunneling spectroscopy to probe the giant Stark effect in atomically-thin materials
Journal
ADV MATER
Date
2020.02.06
Abstract
Each atomic layer in van der Waals heterostructures possesses a distinct electronic band structure that can be manipulated for unique device operations. To fully use the unprecedented and precise device architecture, it remains a challenge to use the modulation of effective bands of each atomic layer for target operations. Here, we report new conceptual spectroscopy at device-scale based on the negligible quantum capacitance of two-dimensional semiconductors in lattice-orientation-tuned, vertical resonant tunneling transistors. Effective band structures of mono-, bi-, and quadrilayer of MoS2 and WSe2, modulated by the orientation- and external electric field-dependent interlayer coupling in device operation, could be demonstrated overcoming former optical, photoemission, and tunneling spectroscopy. Debatable quasiparticle effects from excitons and phonons are excluded in the transport spectroscopy, revealing pristine bandgaps of monolayer MoS2 (2.02 eV) and WSe2 (1.64 eV). Thus, the interlayer coupling in vertical heterostructures becomes a new and practical ingredient for 2D device applications.