Research

The structure of our research

Topic 1: Atomic control using electron beam

Introduction: The birth of atom control is symbolized by the construction of the “IBM” logo using Xe atoms via scanning tunneling microscope. However, since then, the STM-enabled technologies did not extend atom control further to the device-level as a result of two critical issues: (1) Ultra-low temperature and ultra-high vacuum are required; (2) Single-probe maneuvering is extremely time-consuming. On the other hand, atomic devices and quantum materials should have the following properties to extend the utilities of atomic-engineered materials: (1) stable at room temperature, (2) spatially uniform, (3) controlled on-demand, and (4) having tailored properties. Our goal is to develop an atom fabrication method that allows scaled-up manufacturing inside scanning transmission electron microscope (STEM), which can produce quantum devices and single-atom catalysts. We are working closely with research groups specialized in quantum information sciences and electrochemistry to develop new structures.

Figures: (Top) A schematic showing the single atom control using electron beam. (Bottom) The quantum emitter ensembles created by electron beams, forming a smily face pattern.

References

Nature Materials 21, 896–902 (2022).
Science Advances, 5:eaav2252 (2019).
2D Materials, 9, 035009 (2022).

Topic 2: 2D materials synthesis, doping and applications

Introduction: The production of 2D materials and its derivatives (including substitutional doped 2D materials, stacked van der Waals materials, functionalized 2D materials etc.) controls the upstream of materials research, which usually includes four parts: synthesis, characterization, device fabrication, and theoretical prediction/explanation. Our research involves chemical vapor deposition (CVD) and chemical vapor transport (CVT) to synthesize various kinds of low-dimensional materials, including transitional metal dichalcogenides (pristine and doped), carbon and boron nitride nanotubes, graphene (pristine and doped) etc. Organic coating is also to be used for protecting and functionalizing 2D materials.

Figures: (Top left) The near-1-mm monolayer molybdenum disulfide sample synthesized by halide salt assisted CVD method. (Bottom left) The annular dark field image of V doped MoS2 with V dopant marked by arrows. (Right) A schematic figure of the organic monolayer protecting 2D materials.

References

Science Advances, 7:eabj3274 (2021);
Nature Electronics 5, 28–36 (2022);
PNAS 116, 42 (2019);

Topic 3: Interface of metal and 2D semiconductors

Introduction: Metal-semiconductor contact has been one of the most important topics in nano electronics. We are trying to reduce the contact resistance so that monolayer semiconductor can potentially be used as the next generation semiconductor material. Please read this introduction for more information.

Figures: A schematic diagram shows the transistor structure with a monolayer MoS2 as the channel material and metal electrodes (source and drain) in contact.

References

Nature, 593, 211–217 (2021);