I am more than excited to announce that I have started a faculty position as an Assistant Professor at Hongik University, Seoul, Korea!
I will continue my research with the focus on novel semiconductor and topological materials and their applications for transistor devices.
I will be teaching Digital Logic Circuits (디지털논리회로) and Electrical and Electronic Materials (전기전자재료) this Fall semester
I am grateful that my recent correspondence work led by Professor Chih-Ming Lin from National Tsing Hua University, "Early-onset of pressure-induced metallization in iron-doped multilayered molybdenum disulfide" has been published in Applied Physics Letters.
In this collaborative work, we observed that pressure-dependent phase transitions of Fe-doped MoS2 are greatly accelerated compared to those of pristine MoS2. This work suggests a novel approach to manipulate the magnetic and spin properties of Diluted Magnetic Semiconductor Fe:MoS2, which could be applicable for spintronics and advanced memories.
I am pleased to share that my recent work led by Dr. Michael Moody, "Van der Waals Epitaxy, Superlubricity, and Polarization of the 2D Ferroelectric SnS" has been accepted by ACS Advanced Materials & Interfaces.
This paper investigates the van der Waals epitaxy growth of ferroelectric 2D material SnS on hBN substrates. The van der Waals epi-interface gives rise to superlubricity, where the sliding of the SnS pallets strongly prefers certain crystallographic orientations. 4D-STEM reveals in-plane ferroelectric polarization of the grown SnS.
I am pleased to share that my recent work "Nonvolatile Modulation of Light Emission from Delocalized and Defect-Bound Excitons in Monolayer MoS2 Using the Remnant Polarization in the Ferroelectric Polymer P(VDF-TrFE): Implications for Optical Memory" is now published in ACS Advanced Nano Materials! (lengthy title!)
In this paper, we present that the polarization switching of ferroelectric P(VDF-TrFE) polymer modulates the adjacent MoS2's exciton emissions, namely the free excitons at room temperatures as well as the defect-bound excitons at cryogenic temperatures. The non-volatile modulation of exciton emission suggests a potential application as optical memory with extremely high cell density, where the information is electrically encoded and optically/remotely read out.
I am pleased to inform you that I have started a new research position as Staff Engineer at Samsung Advanced Institute of Technology (SAIT)!
My research "High Performance and Low Power Source-Gatesd Transistors Enabled by a Solution Processed Metal Oxide Homojunction" is now published in the Proceedings of the National Academy of Sciences (PNAS)!
In this work, I applied a functional scanning probe characterization technique to reveal the operating principle of solution-processed In2O3 TFT. Doping- and contact-engineered solution-processed In2O3 TFTs performed strong output saturation, which allows for <1V of operating voltage and ≈25 μW of operating power. Operando-KPFM revealed that the exceptional output saturation is due to the Schottky barrier at the source contact, i.e., the device was operating in a source-gated transistor (SGT) regime. This work will provide a novel approach for low-cost power-efficient TFTs.
My work "Edge and Interface Resistances Create Distinct Trade-Offs When Optimizing the Microstructure of Printed van der Waals Thin-Film Transistors" is published in ACS Nano!
In contrast to the excellent electronic transport performance of single-sheet MoS2 FETs, MoS2 (or any other 2D semiconductor)-based printed TFTs suffer from poor electrostatic gating, low mobility, and/or high off-current. This paper, led by Zhehao Zhu, investigates the mechanism of such performance degradation of printed films, via a combination of scanning probe microscopy characterization and resistor network modeling. The charged edges of MoS2 flakes induce an electrostatic gating effect on adjacent flakes, causing performance degradation.
I presented my work "Reconfigurable Source-Gated Transistor Based on 2D Ferroelectric Heterostructure" at the MRS Fall Meeting in Boston. In the talk, I shared how the power efficiency of monolayer MoS2 FETs can be further enhanced, by the formation of heterojunction with ferroelectric semiconductor α-In2Se3.
I am excited to share that my work "Strain-Modulated Interlayer Charge and Energy Transfers in MoS2/WS2 Heterobilayer" is now published online in ACS Applied Materials & Interface!
Charge and energy transfers are physical phenomena that define the optical and electronic properties of 2D heterostructures. By the use of compressive strain, the interaction between monolayer MoS2 and WS2 has been greatly enhanced, resulting in non-monotonic, selective modulation of charge and energy transfer. This is an innovative approach (i.e., mechanical) to modulate the 2D heterostructures' properties that can be adopted for mechanical sensors and straintronics.
I am pleased to share that my collaborative research "Readily Accessible Metallic Micro Island Arrays for High-Performance Metal Oxide Thin-Film Transistors" was published in Advanced Materials!
I presented my recent research at the MRS Fall Meeting, titled "Localization and Modulation of Excitonic Emission in MoS with Mixed-Dimensional Ferroelectric Heterostructures". I presented how ferroelectric switching reconfigures excitonic emissions in monolayer MoS₂.