Meet Younghwan Lee

Tell me a little about yourself!

I am a third year Ph.D. student in the Materials Science and Engineering department, working in Dr. Jacob Jones’ research group. My research includes the fabrication of ferroelectric HfO2-based thin films and their structural- and electrical-properties characterization using various techniques such as ToF-SIMS, XPS, TEM, XRD and x-ray synchrotron. After finishing my Ph.D. degree, I would like to extend my career in the academic field. Outside of my work, I like to play guitar and watch movies late at night.

What instrument(s) are you using for your research and why do you like it?

I particularly like the x-ray diffractometer among other instruments including XPS (X-ray photoelectron spectroscopy) and TEM (Transmission Electron Microscope) since it is very efficient instrument.  X-ray diffraction does not require burdensome preparation, such as pumping down the instrument to make a vacuum system, yet it provides a lot of information about a material. By interpreting the XRD data I can characterize my sample through properties such as crystallinity, phase, existence of strain, crystallite size and preferential crystallographic-orientation of the materials. I think it is very useful and powerful technique.

What have you been researching and how is it impacting the community?

I am working on the fabrication of doped HfO2 and (Hf,Zr)O2 thin films using Atomic Layer Deposition (ALD). I use various characterization techniques, such as in situ XRD, TEM and x-ray synchrotron, to study the structural properties of fabricated thin films. I am also studying the ferroelectric and piezoelectric property of HfO2 in order to find new applications including sensors, actuators and electronic devices. Recently, I am focusing on the effects of a capping layer, which can be textured with different crystallographic-orientation, on HfO2-based thin films.

My research is focused on the development of new capacitors and verifying its properties by using various characterization techniques. In addition, the increased performance capabilities will likely downsize the device, which result in more flexibility for device design.

Since this type of capacitor can be used to develop the performance of data storage devices in computers, it is expected to lower the power consumption significantly and save energy.

What have you learned from your experience at AIF?

I learned that understanding the working principles of characterization techniques is as important as understanding the material. This is because the data acquired from one characterization technique always contains the systematic error, which is caused by different measurement conditions. For example, the data we obtain from each measurement can show different results although the sample is the same. This problem can be solved if we have enough background knowledge of the characterization technique and the instrument being used. I learned how to interpret the data appropriately by considering many factors that can influence the results such as wrong calibration, sample displacement, type of detector, etc.

XRD and TEM result of TIN made by N2 and H2 atmosphere

Best thing about AIF in 5 words or less?

Cooperative experience with knowledgeable staff

Is there a staff member at AIF that has helped you?

I would like to thank everyone in the AIF whom I have worked with. Especially, I send my appreciation to BB and Phillip for their immediate and helpful responses all the time.