I am a Ph.D. student in the Department of Physics at Stanford University. Currently I am working in the group of Prof. Tony Heinz. I am interested in studying opto-electronic properties and emergent phenomena in novel two-dimensional van der Waals heterostructures. My current research focuses on transition metal dichalcogenide (TMD) homo- and heterobilayers. I completed my B.S. in Physics from Harvard University where I worked in the group of Prof. Philip Kim on interlayer excitons in WSe2/MoSe2 heterostructures and quantum transport in WSe2 mono- and twisted homobilayers.
Education & Certifications
Bachelor of Science, Harvard University, Physics (2018)
Electrical control of interlayer exciton dynamics in atomically thin heterostructures.
Science (New York, N.Y.)
2019; 366 (6467): 870–75
A van der Waals heterostructure built from atomically thin semiconducting transition metal dichalcogenides (TMDs) enables the formation of excitons from electrons and holes in distinct layers, producing interlayer excitons with large binding energy and a long lifetime. By employing heterostructures of monolayer TMDs, we realize optical and electrical generation of long-lived neutral and charged interlayer excitons. We demonstrate that neutral interlayer excitons can propagate across the entire sample and that their propagation can be controlled by excitation power and gate electrodes. We also use devices with ohmic contacts to facilitate the drift motion of charged interlayer excitons. The electrical generation and control of excitons provide a route for achieving quantum manipulation of bosonic composite particles with complete electrical tunability.
View details for DOI 10.1126/science.aaw4194
View details for PubMedID 31727834
- Guided Modes of Anisotropic van der Waals Materials Investigated by near-Field Scanning Optical Microscopy ACS PHOTONICS 2018; 5 (4): 1196–1201
Probing dark excitons in atomically thin semiconductors via near-field coupling to surface plasmon polaritons
2017; 12 (9): 856-+
Transition metal dichalcogenide (TMD) monolayers with a direct bandgap feature tightly bound excitons, strong spin-orbit coupling and spin-valley degrees of freedom. Depending on the spin configuration of the electron-hole pairs, intra-valley excitons of TMD monolayers can be either optically bright or dark. Dark excitons involve nominally spin-forbidden optical transitions with a zero in-plane transition dipole moment, making their detection with conventional far-field optical techniques challenging. Here, we introduce a method for probing the optical properties of two-dimensional materials via near-field coupling to surface plasmon polaritons (SPPs). This coupling selectively enhances optical transitions with dipole moments normal to the two-dimensional plane, enabling direct detection of dark excitons in TMD monolayers. When a WSe2 monolayer is placed on top of a single-crystal silver film, its emission into near-field-coupled SPPs displays new spectral features whose energies and dipole orientations are consistent with dark neutral and charged excitons. The SPP-based near-field spectroscopy significantly improves experimental capabilities for probing and manipulating exciton dynamics of atomically thin materials, thus opening up new avenues for realizing active metasurfaces and robust optoelectronic systems, with potential applications in information processing and communication.
View details for PubMedID 28650440
Low-Temperature Ohmic Contact to Monolayer MoS2 by van der Waals Bonded Co/h-BN Electrodes
2017; 17 (8): 4781–86
Monolayer MoS2, among many other transition metal dichalcogenides, holds great promise for future applications in nanoelectronics and optoelectronics due to its ultrathin nature, flexibility, sizable band gap, and unique spin-valley coupled physics. However, careful study of these properties at low temperature has been hindered by an inability to achieve low-temperature Ohmic contacts to monolayer MoS2, particularly at low carrier densities. In this work, we report a new contact scheme that utilizes cobalt (Co) with a monolayer of hexagonal boron nitride (h-BN) that has the following two functions: modifies the work function of Co and acts as a tunneling barrier. We measure a flat-band Schottky barrier of 16 meV, which makes thin tunnel barriers upon doping the channels, and thus achieve low-T contact resistance of 3 kΩ.μm at a carrier density of 5.3 × 1012/cm2. This further allows us to observe Shubnikov-de Haas oscillations in monolayer MoS2 at much lower carrier densities compared to previous work.
View details for PubMedID 28691487