Research

Research

Our research interests center on developing advanced materials characterization techniques, in particular, those based on transmission electron microscopy (TEM) and electron diffraction, with the ultimate goal to advance the understanding and accelerate the discovery of novel, functional materials. Our group is particularly specialized in utilizing electron microscopy data in a truly quantitative way. Shown below are some of our recent research interests.

Topic 1: Atomic Structure and Functionality of Point Defects

Point defects play a key role in determining the properties of nearly all materials, from electron and ionic transport to radiation effects in structural materials. Detection of individual point defects has been a long-sought-after goal in transmission electron microscopy. However, detection of point defects, especially, isolated light elements or vacancies, is a formidable challenge due to the limited detection efficiency and inherent noise in modern transmission electron microscopy.

Our group focuses on the development of novel TEM imaging and data analysis techniques with atomic-scale spatial resolution, high measurement precision, and single-atom sensitivity to enable the detection of point defects, revealing their effects on local structure and symmetry, and unveiling the structure-property correlation.

Potential application of these techniques to new functional materials will resolve key questions, such as the microscopic origin of the limited dopant activation in new transparent conduction oxides, or the role of point defects and surface structure in perovskite quantum dots.

Topic 2: Polarization Switching Dynamics in Ferroelectric Thin Films

Every year, the amount of stored and processed digital information continues to grow significantly. This trend is further accelerated by the recent development of data-intensive computing technologies such as artificial intelligence (AI). To keep pace with the ever-increasing data, there is a critical need to develop (1) novel computing systems with low power consumption and efficient data processing and (2) memory devices with high data capacity and fast read/write speed, and non-volatility. Ferroelectric materials (in thin-film form) have gained tremendous interest as candidates for next-generation synaptic devices that serve as memory units in neuromorphic computing systems.

Our group focuses on uncovering the mechanisms of ferroelectric domain formation and polarization switching dynamics using advanced imaging methods in TEM (e.g., in situ biasing and 4D-STEM). The materials system that we are currently working on includes doped hafnia, ScAlN, and improper ferroelectric material (.e.g., YMnO3).

Topic 3: Defects in Ultra-Wide Bandgap Semiconductors for Power Electronics

Semiconductors with wide bandgaps and excellent transport properties can withstand high electric fields and currents, and offer high switching speed, thus making them ideal platforms for next-generation power electronics. Power devices typically operate in harsh environments (e.g., high electric fields); as a result, defects can nucleate, evolve, and interact by external stimuli under realistic operation conditions. Thus, it is critical to characterize crystal defects and produce a fundamental understanding of the effects of defects on materials properties and device performance. Our group currently focuses on characterizing defects in beta-phase gallium oxide in order to elucidate the mechanisms of defect formation and electrical activity. 

Topic 4: Materials Dynamics in Energy Materials

To be updated

Topic 5: Computer-Vision and Machine-Learning Enabled TEM Data Processing

To be updated