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Our research has two integrated components: (1) Nanomaterial sysnthesis and nanoscale fabrication and (2) Electrical and optical measurement. Our expertise on material sysnthesis and nanoscale fabrication enables us to design structures/devices which are suitable for our electrical and optical study. We are also constantly developing unique electrical and optical measurement tools which can best characterizing electron-photon interactions in low dimensions. The obtained knowledge, in return, helps us to propose and fabrication novel nanoscale electronic and optoelectronic devices that are promising for future applications.

Nanomaterial Synthesis

We use mechanical exfolation of bulk single crystal or chemical vapor deposition to produce atomically thin materials. These high quality materials form the critical foundation for our research. 1) Mechanical exfoliation is a simple yet powerful to produce various two-dimensional (2D) materials from bulk single crystal. It also provides a flexible method to combine different 2D material to form van der Waals heterostructures, through which we can design materials with atomic resolution. 2) Chemical vapor depostion (CVD) provides a way to produce high quality 2D materials over large scale which greatly facilitate our research. More importantly it potential leads to real applications.

Nanoscale Fabrication

We build nanometer scale devices with precise control provided by state-of-art fabrication tools. We also develop fabrication tools in our lab, such as electromigration technique, to go beyond the resolution of ebeam lithography to make devices down to atomic scale. This capability, combined with our nanomaterial synthesis, provides a powerful platform to investigate quantum effects in spatially confined materials. This understanding not only reveals interesting physics in low dimensions but also guides new materials and new devices design. In return, we can implement this understanding with our fabrications capability to create novel electronic or opto-electronic devices for applications.

Electrical and Optical Measurements

We perform low temperature transport measurement to reveal quantum effects in nanoscale devices. We hope to apply the obtained knowledge to design nanoelectronic devices with new applications. We also perform broadband (visible to terahertz) and ultrafast (~100s fs) optical spectroscopy of nanomaterials (mostly 2D materials) to understand light matter interaction in low dimensions. Most importantly, we combine these two and develop spatially resolved and time resolved photo-current measurement to investigate photocurrent generation at nanoscale devices with ultrafast time resolution.