Plenary Talk - 8 

Two-Dimensional High-k Dielectric Materials 

J.K. Huang, J.J. Shi. J. Zhang and S. Li 

UNSW Materials and Manufacturing Futures Institute, The University of New South Wales

The scaling of silicon metal–oxide–semiconductor field-effect transistors has followed Moore’s law for decades, but further thinning of silicon at sub-ten-nanometre technology nodes incurs detrimental issues such as leakage current. Two-dimensional (2D) layered semiconductors, with an atomic thickness that allows superior gate-field penetration, are of interest as channel materials for future transistors. However, the integration of high-dielectric-constant (κ) materials with 2D materials, while scaling their capacitance equivalent thickness (CET), remains challenging. Here we exploit transferrable ultrahigh-κ single-crystalline perovskite strontium-titanium-oxide membranes as a gate dielectric for 2D field-effect transistors. Our perovskite membranes exhibit a desirable sub-one-nanometre CET with a low leakage current (less than 10⁻² amperes per square centimetre at 2.5 megavolts per centimetre). We find that the van der Waals gap between strontium-titanium-oxide dielectrics and 2D semiconductors mitigates the unfavourable fringing-induced barrier-lowering effect resulting from the use of ultrahigh-κ dielectrics. Typical short-channel transistors made of scalable molybdenum-disulfide films by chemical vapour deposition and strontium-titanium-oxide dielectrics exhibit steep subthreshold swings down to about 70 millivolts per decade and on/off current ratios up to 10⁷, fulfilling the low-power requirement specified in the latest International Roadmap for Devices and Systems.

About the speaker:

Professor Sean Li is the director of UNSW Materials and Manufacturing Futures Institute at the University of New South Wales, Sydney, Australia. He is leading the futures institute to transform the future of materials and manufacturing research from manipulation of atomic arrangements to device fabrication and high throughput industry scale manufacturing. He has invented several game-changing technologies that have already been licensed and used by industry. As a leading academic, Professor Li has published his works in the prestigious journals of the field, including “Nature”, “Science”, “Progress in Materials Science”, “Energy and Environmental Science” and “Advanced Materials” etc. His laboratory is equipped with unique and world-class research facilities, and it is the most advanced laboratory of its type in Australia. The breadth, depth and variety of these facilities mean that he has established UNSW as preeminent in Australia in the area of two-dimensional high-k dielectric materials.