1. High-Performance Infrared Photodetectors
Infrared photodetectors and imaging sensor arrays (for wavelengths over the range 1-14 μm) have been found to be critical in a wide range of applications including night-vision, remote sensing, optical communications, and emerging medical imaging modalities. Semiconductors in devices and arrays for infrared photodetectors are dominated by single-crystalline Ge and III-V semiconductors such as InGaAs, InGaAsP, and HgCdTe. However, these materials are typically grown by complex methods, including molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD), resulting in complicated manufacturing procedures and subsequent high cost. Our aim is to develop novel material systems, which can combine the simple preparation procedure and high device performance, for fabrication of high-performance and low-cost infrared photodetectors, focal plane arrays and imaging sensor systems. We focus on the science and technology challenges lying in optimizing the device performance of photodetectors, focal plane arrays and imaging sensor systems by materials engineering, device structure engineering and circuit design.
2. Large-Area Electronics based on Thin Film Semiconductors
Exploring low-temperature (400 oC or lower) grown semiconductor thin films with high mobility and device performance is of great importance for a number of applications including transparent/flexible electronics, and monolithic three-dimensional (3D) complementary metal-oxide-semiconductor (CMOS) architectures. Multiple n-type material systems with respectable electron mobility on the order of 10 cm2V-1s-1, such as a-IGZO, a-ZnO, InOx, CdS and CdSe, have been identified, but the development in their p-type counterparts has been still limited despite many years of efforts. Our aim is to develop p-type semiconducting thin films that can be processed at near ambient temperature with high mobility and device performance for the fabrication of high-performance field-effect transistors (FETs), logic gates and circuits, 3D CMOS circuits, transparent electronics and flexible electronics. We focus on the science and technology challenges lying in optimizing the devices or circuits performance by materials engineering, device structure engineering and circuit design.
3. Novel Functional 2D Materials
Ultrathin two-dimensional (2D) materials represent an emerging class of nanomaterials that possess sheet-like structures with the lateral size larger than 100 nm, or up to few micrometers and even larger, but only single- or few-layer atomic thickness (typically less than 5 nm). The 2D feature is unique and indispensable to access unprecedented physical, electronic, and chemical properties due to electron confinement in two dimensions. However, the controlled synthesis of ultrathin 2D nanomaterials with desirable structural characteristics is still difficult to be realized by most of currently well-developed methods. We focus on the rational design and synthesis of novel 2D materials with desirable structural characteristics, such as size, layer number, defects, vacancies and phase, to achieve high performance in a number of applications such as electronics/optoelectronics, cancer therapy, electrocatalysis and energy storage.