Research

  Our focus lies in the utilization of chemical methods for developing materials and devices for electronic and energy applications.
Specifically, our current research interests include:
1. The use of atomic layer deposition (ALD) to deposit various functional materials, such as dielectric and metallic films.
2. In-situ analytical studies to investigate surface reactions in the ALD process, using in-situ analytical techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Quartz Crystal Microbalance (QCM), and Quadrupole Mass Spectrometry (QMS).
3. Exploring diverse industrial applications of the ALD process, including transistors, memories, catalysts, gas diffusion barriers, solar cells, fuel cells, etc.

  ALD is a specialized form of chemical vapor deposition (CVD) that enables precise and self-limiting growth of thin films. In the ALD method, the substrate temperature (typically between 150 to 300°C) is maintained below the thermal decomposition temperature of the precursor. This ensures that the film growth occurs primarily via chemisorption of the precursor onto functional groups present on the substrate's surface, rather than due to the precursor's thermal decomposition.

  For oxide thin films, a typical cycle in the ALD process involves four steps (as shown in the left figure): 1) feeding metal-organic precursors, 2) purging the reactor to remove excess precursors and byproducts, 3) feeding oxidant gas, and 4) purging the reactor again. By repeating this cycle, thin films can be grown with high thickness control in the angstrom scale. Additionally, the growth rate of thin films in the ALD process is self-limited, meaning that it remains independent of the amount of precursor supplied.

  Thanks to this self-limiting behavior, ALD films exhibit excellent conformality on complex 3D structures, as shown in the right figure depicting Ru thin films grown on amorphous carbon nanotubes. Our research aims to utilize ALD for developing dielectric and metallic thin films for electronic and energy applications and explore the synthesis of nano-materials using ALD techniques.