Research

Research Interest

Photovoltaics, material-based hardware security, photonics, metamaterials engineering, and anti-counterfeiting technologies

▷ Nano/microstructure fabrication and characterization

  • Antireflection (AR) subwavelength structures, nanorods, and compound eye architectures / highly-reflective distributed Bragg reflectors using nanoporous films / highly-transparent glasses and polymers with AR nanostructures / physical characterization of transparent conducting oxides.

▷ Applications I : optoelectronic systems (solar cells, LEDs, LDs, and photodetectors)

  • Efficiency enhancement of solar cells and light-emitting diodes using AR nano/microstructures / Nanogenerators and optical sensors with nano/microstructure architectures / plasmonic photogenic metamaterials for photoelectric conversion.

▷ Applications II : antimicrobial systems

  • Development of photosensitizing metamaterials and their applications.

▷ Applications III : hardware securty systems

  • Biocompatible and edible cryptosystems for anti-counterfeiting in pharmaceutical and security areas.

  • 2D nanomaterials-based crypgraphic primitives (i.e. physical unclonable functions).

▷ Numerical modeling and simulations

  • Device design and analysis of Si and III-V solar cells using Silvaco ATLAS / Optical analysis of nano/microstructures using RCWA/FDTD method.


Technical Expertise

▷ Programming/Simulation software

  • Matlab and Labview / DiffractMod (RSoft, RCWA method), FullWave (Rsoft, FDTD method) / Silvaco ATLAS (Silvaco, Semiconductor device simulator) / ADS and AutoCAD Mask Design.

▷ Process techniques

  • Patterning : Soft imprint lithography, laser interference lithography, photo-lithography

  • Deposition : Electrochemical deposition, plasma-enhanced chemical vapor deposition, thermal chemical vapor deposition, RF/DC magnetron sputtering, electron-beam evaporation, thermal evaporation.

  • Etching : Reactive ion etching, inductively coupled plasma etching, wet chemical etching.

  • Synthesis : Metal/semiconductor nanomaterials synthesis (hydrothermal, electrochemical).

  • Oxidation/treatment : Furnace, wet/dry thermal oxidation, rapid thermal annealing, wafer lapping and polishing, wafer dicing and wire bonding.

  • System set-up : Most of semiconductor high vacuum equipment, measurement systems of LDs, LEDs, images, spectra, and etc.

▷ Characterization tools

  • SEM, TEM, AFM, XRD, surface profiler.

  • UV-VIS-NIR spectrophotometer, Photoluminescence, Hall measurement, Ellipsometry, Confocal microscopy.

  • L-I-V measurement for LDs and LEDs.

  • Solar simulator, QE measurement, and nanogenerator measurement.

▷ Nanostructure Fabrication and applications

• Antireflective subwavelength structures & compound eye structures

• Low-dimensional nanostructures: nanorods & nanoporous films

• Micro- and nanostructures using soft lithography

• Device & Optical modeling/analysis

▷ Scalable plasmonic biomaterials

▷ Genetic hybridized photocatalytic biomaterials using silk and fluorescent proteins

▷ Edible unclonable function based on proteins for anti-counterfeiting

Research Activities

  • Development of security technologies using fluorescent silk for anti-counterfeiting and authentication (June 2020 – Dec. 2022)

  • Scalable production and deposition of luminescent silk microparticles for ‘on-dose’ medicine authentication (June 2020 – Nov. 2020)

  • Integrated approaches of physically unclonable cryptographic primitives using random lasers and optoelectronics (Aug 2017 – July 2020)

  • Wearable biosensing platforms using 2D native protein fibers (July 2016 – June 2017)

  • Development of photocatalytic multifunctional fabrics for pathogenic microorganism inactivation using transgenic fluorescent silk (Jan. 2016 – Dec. 2018)

  • Development of functional hierarchical metal-oxide nanostructure based flexible/stretchable optical sensing device technologies (June 2013 – Sep. 2015)

  • Development of 960 nm and 975 nm band 20 W high power semiconductor laser chip for pumping that has more than 60% efficiency of photoelectric transformation (May 2013 – Sep. 2015)

  • The development of 200 mW level high power green (525 nm) LED for full color display (May 2012 – Feb. 2014)

  • Development of 30% III-V compound solar cell using the method of Ge over-lateral growth (Dec. 2011 – Nov. 2013)

  • Fabrication of nano surface structures and optimum design of highly efficient quantum-dot solar cell (Sep. 2011 – Aug. 2013)

  • Development of compound semiconductor solar cells with broadband antireflection subwavelength grating (SWG) (May 2009 – Apr. 2012)

  • Study on the development of semiconductor lasers based on superlattices in long infrared wavelengths (8–12 mm) for free space optical (FSO) communication (May 2008 – Feb. 2011)