In brief

Liquid-metal printed high-κ gallium oxide films achieved atomically smooth interfaces to enhance the efficiency and miniaturisation of two-dimensional semiconductor devices.

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Smooth operators: high-performance semiconductors for nanoelectronics

18 Dec 2023

Researchers pioneer new pathways towards miniaturised electronics with a scalable, high-efficiency liquid-printing technology for semiconductor manufacturing.

Mobile phones have undergone a remarkable evolution from the bulky bricks of the 1980s to today’s sleek, palm-sized powerhouses. Two-dimensional semiconductors have been the backbone behind this miniaturisation. These ultrathin materials can be used to shrink complementary metal-oxide semiconductor circuits for powering a kaleidoscope of efficient, high-performance nanoelectronics.

However, experts say materials currently used to fabricate 2D semiconductor materials have reached a tipping point. Without scalable high-κ dielectrics (insulating materials with the ability to hold an electric charge), the full potential of 2D semiconductors remains untapped.

“When such insulators are integrated with 2D semiconductors, they often lead to defective films, resulting in slow devices that waste energy,” said Aaron Lau, a Senior Scientist and Emerging Group Leader at A*STAR’s Institute of Materials Research and Engineering (IMRE). “Furthermore, traditional methods of combining the two components can cause physical damage, leading to device failure.”

Lau and IMRE colleagues collaborated with Michel Bosman from the National University of Singapore and Ang Yee Sin from the Singapore University of Technology and Design to explore ways of packing more electronic performance into tinier gadgets.

To achieve this, they developed a new liquid-metal printing technique for gallium oxide (Ga2O3), a semiconductor-compatible high-κ dielectric material ideal for advanced electronic applications.

“The unique advantage of liquid metals is their ability to coat surfaces like paint, creating a dielectric layer that conforms perfectly to the semiconductor beneath it,” said Lau, adding that the smoothness of the Ga2O3 layer is critical for enhancing the performance and reliability of electronic devices.

“This essentially allows the liquid metal to fill any nanometre-sized gaps and avoid bubbles,” Lau added.

Their liquid-metal printing technology achieved incredibly thin and uniform Ga2O3 layers, coupled with cutting-edge scalability. “If the film had the thickness of a human hair, we could print it over an area roughly the size of a tennis court, and its thickness would not vary by more than 10 percent,” said Lau.

The team’s novel semiconductor also achieved low subthreshold swings and gate leakage currents, properties which can translate to compact, super-efficient transistors of the future.

Lau’s team is eager to explore the synthesis of other oxides using their novel approach and to investigate its potential computing applications such as quantum-information processing. “This could pave the way for 2D semiconductor-based quantum computers, a thrilling prospect that drives our research forward.”

The A*STAR-affiliated researchers contributing to this research are from the Institute of Materials Research and Engineering (IMRE).

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Zhang, Y., Venkatakrishnarao, D., Bosman, M., Fu, W., Das, S., et al. Liquid-metal-printed ultrathin oxides for atomically smooth 2D material heterostructures. ACS Nano, 17 (8), 7929–7939 (2023).│article

About the Researchers

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Aaron Lau

Senior Scientist II and Emerging Group Leader

Institute of Materials Research and Engineering
Aaron Chit Siong Lau is Senior Scientist II and Emerging Group Leader at the Institute of Materials Research and Engineering (IMRE). He is an Investigator at the A*STAR Quantum Innovation Centre (Q.InC). Graduating with a DPhil in Materials from the University of Oxford, UK in 2017, his current research interests are in quantum information processing, quantum transport, quantum materials, and nanofabrication of low-dimensional systems.
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Johnson Goh

Division Director and Senior Principal Scientist

Institute of Materials Research and Engineering (IMRE)
Johnson Kuan Eng Goh is the Division Director and Senior Principal Scientist at the Institute of Materials Research and Engineering (IMRE). He is Adjunct Professor at the School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore. He also serves as the Director of the Quantum Engineering Programme funded by the National Research Foundation, Singapore. He holds a PhD in Physics (2007) from the University of New South Wales, Australia; his current research interests are in quantum computation, valleytronics, and quantum effect devices.

This article was made for A*STAR Research by Wildtype Media Group