Excitonic Transistor

We developed the first excitonic transistors capable of operating at room temperature by exploiting the unique properties of 2D van der Waals heterostructures. By utilizing a MoS₂-WSe₂ stack, we created long-lived interlayer excitons with a permanent out-of-plane dipole moment. This architecture allowed us to demonstrate an effective excitonic switch where the flux of these neutral quasiparticles is controlled via an external electric field. We achieved an ON/OFF ratio exceeding 100 at room temperature, limited only by the measurement noise floor. Building on this platform, we also realized comprehensive electrical control over the valley-state of interlayer excitons. By resolving separate interlayer transitions with opposite helicities, we successfully demonstrated a gate-tunable polarization switch. This device can alternate between polarization-inverting and polarization-preserving regimes, providing a critical building block for encoding information in the valley degree of freedom—a field known as valleytronics. This research bridges the gap between traditional electronics and purely optical systems, offering a path toward integrated excitonic circuits that combine the high speed of optics with the scalability of solid-state devices.

Project Technical Profile

Core Skills: Quantum Device Design, vdW Heterostructure Fabrication, Low-T/UHV Cryogenics, Valley-Polarized Spectroscopy.
Key Achievement: Demonstrated room-temperature exciton flux control (Nature, 2018) and the first gate-tunable valley polarization switch (Nature Photonics, 2019).