Growth of h-BN and its applications
Growth of h-BN (MOCVD)
h-BN based Photonics
h-BN based Electronics
Growth of h-BN: Hexagonal boron nitride (h-BN) has emerged as a highly promising two-dimensional material due to its unique physical properties and potential applications in electronics, photonics, and optoelectronics. In our laboratory, we are focusing on developing a growth technique called metal-organic chemical vapor deposition (MOCVD) to deposit h-BN on various substrates. Current research focuses on investigating the impact of the substrate, growth chemistry, and processing conditions on nucleation and growth, as well as characterizing the optical and electrical properties of the grown h-BN.
h-BN-based photonics: Recently, h-BN has attracted intensive research interest due to its wide range of outstanding properties exhibited in the fields of photonics and optoelectronics across various wavelengths. In our laboratory, we are interested in studying the optoelectronic properties of excitons, which can be generated through photoexcitation or electrical injection. Our studies focus on designing the device structure of electrically-driven light-emitting devices and photodetectors to study the behavior of excitons in h-BN and develop high-performance h-BN-based optoelectronic devices.
h-BN-based electronics: h-BN has gained considerable attention as a resistive switching layer for memristive devices. In our laboratory, we concentrate on developing high-performance h-BN-based memristors, utilizing MOCVD-grown h-BN. We demonstrate wafer-scale h-BN-based memristors with a unique device structure that showcases outstanding memristive performance. Additionally, we address the ongoing challenges of conventional metal-oxide-based memristors with a fundamental study on switching phenomena.
Micro LEDs for AR/VR Displays
III-Nitride-based Micro-LED
Micro LEDs have emerged as promising candidates for next-generation displays owing to their superior brightness, high contrast ratio, long lifetime, and rapid response time compared to LCD and OLED. However, there is a substantial decrease in the external quantum efficiency (EQE) as the size of µLED is reduced.
One of the factors responsible for this reduction is the increase in the proportion of damaged sidewalls generated during the inductively coupled plasma (ICP) dry etching process. One of the main research goals is to investigate the efficiency reduction mechanism in micro LEDs and enhance their efficiency by identifying sidewall defects that depend on the conditions of the ICP etching process.
3D Nanostructures for Energy and Environment
3D nanostructures
Electrocatalyst
Gas Sensors
Synthesis of 3D Nanostructures: Another research goal is to explore and design novel catalytic, electrical, and optical properties of nanostructured materials for energy and environmental applications. More specifically, we use the oblique angle deposition technique to design well-ordered nanostructures consisting of various materials and morphologies, and their hierarchical combinations to enhance the performance of energy/environmental materials.
(Photo-)Electrocatalysts: With global warming and the energy crisis, there are strong demands for clean and renewable energy sources like hydrogen. (Photo-)electrochemical water splitting has been regarded as a promising technology to produce green hydrogen fuel. (Photo-)electrochemical CO2 reduction using renewable electricity offers an attractive approach to producing widely needed chemicals and feedstocks, such as CO, CH4, and HCOOH, while mitigating greenhouse gas emissions. For efficient water splitting and CO2 reduction, we develop 3D nanostructures based (photo-)electrocatalysts and investigate their reaction mechanisms to optimize catalytic performance.
Gas Sensors: Growing demand for portable and cost-effective gas sensors in internet of things (IOT) applications has garnered significant attention for metal oxide (MOX)-based gas sensors as promising candidates. To further enhance the sensing performance of MOX-based gas sensors, it is desirable to use nanostructured MOX with large surface areas as a sensing material. Therefore, we employ the OAD technique to fabricate three-dimensional (3D) nanostructured MOX and strategically design the device structure and materials to improve the sensitivity and selectivity of the gas sensor.