Owing to advantages of wide bandgap, high carrier mobility, and stable chemical properties of III-group nitrides, GaN-based light emitting diodes (LEDs) have the characteristics of high efficiency, high power, high frequency, high operating temperature, and long lifetime. As self-emitting solid-state semiconductor devices, GaN-based LEDs have become a important research and industry orientation in lighting and display field. In the past ten years, micro-LED has shown great advantages in the field of display due to the shrink of sizes or pitches. GaN-based micro-LED possesses higher efficiency, lower energy consumption compared to liquid crystal display (LCD) and higher brightness, longer lifetime compared to organic light emitting diode (OLED) display. With maturity of the substrate transfer and pick-and-place technique (mass transfer), GaN-based micro-LED will be a promising candidate for next gerneration of head-up display (VR/AR), wearable display (flexible), and projector display.
Research topic:
1. Materials: Structure design and selective area growth of nitride heterostructures/Adjustable growth of passivation film by atomatic layer deposition(ALD)/Growth of conductive films like metals, ITO, IZO, IGZO by physical vapor deposition(PVD)
2. Devices: Design and fabrication of face-up, flip-chip, vertical devices with top-down and bottom-up process
3. Arrays: Compact monolithic integration of micro-LED display with active-matrix-addressing mode/ Mass transfer using Nano-imprinting lithography(NIL) technology/development of transparent wearable display
4. Display systems: Design of analog front-end circuit/ Design of MCU for driver chip/ Development of display algorithm (such as De-Mura/GMA, etc.)/ Packaging of display module
Visible Light Communication:
With the increasing shortage of electromagnetic wave communication frequency band resources and the severe safety problem of signal transmission, light fidelity (LiFi) or visible light communication (VLC) technique is expected to be the next generation of high speed and safe communication mode. The basic architecture of VLC technology is to encode and modulate high-frequency optical signals first, then the optical signal reaches the photodetector (usually a photodiode) and is received. Finally, the purpose of signal transmission has been achieved through encoding and modulation post-processing. The lower resistance−capacitance (RC) constant and short carrier lifetime lead to a high modulation bandwidth of micro-LEDs as transmitters for high-speed communication. In addition, low-dimensional materials such as nanowires and two-dimensional materials have emerged in the field of photoelectric detection. Due to the bandwidth of the visible spectrum and high carrier mobility, low-dimensional materials have shown application potential in the receiving end of VLC.
Research topic:
1. Design and fabrication of individual and structured signal device/Improving cut-off frequency, modulation bandwidth, and transmission rate
2. Digital-analog hybrid circuit design, realizing front-end encoding, modulation and pre-equalization, medium and optical waveguide design, improving light extraction and transmission efficiency
3. Monolithic integration of the transmitter and receiver, the monolithic integration of self-powered visible light detectors and micro-LED transmitter modules based on low-dimensional heterojunction materials, developing high-speed multiple-input multiple-output (MIMO) VLC systems