A research team at the Institute for Basic Science (IBS) has made a significant breakthrough in epitaxial growth, allowing for the synthesis of metallic 1D mirror twin boundaries (MTBs) with a width of less than 1 nm. This breakthrough has paved the way for the development of a new structure for 2D semiconductor logic circuits. The team's findings, published in Nature Nanotechnology, highlight the use of these 1D metals as gate electrodes in ultra-miniaturized transistors.

Integrated devices based on 2D semiconductors have been a major focus of research due to their exceptional properties even at the atomic scale. However, achieving ultra-miniaturized transistor devices that can control electron movement within nanometers has posed technical challenges. The width and control efficiency of the gate electrode, which regulates the flow of electrons, determine the level of integration in semiconductor devices. Traditional fabrication processes face limitations in lithography resolution when reducing the gate length to a few nanometers.

To overcome these limitations, the research team focused on the mirror twin boundary (MTB) of molybdenum disulfide (MoS2), a 2D semiconductor. The MTB was found to be a 1D metal with a remarkable width of only 0.4 nm. Leveraging this discovery, the team utilized the MTB as a gate electrode, surpassing the restrictions of lithography processes.

The achievement of the 1D MTB metallic phase involved controlling the atomic-level crystal structure of the existing 2D semiconductor, transforming it into a 1D MTB. This breakthrough not only holds promise for next-generation semiconductor technology, but also showcases advancements in basic materials science by demonstrating the artificial control of crystal structures to synthesize new material phases on a large scale.

According to the International Roadmap for Devices and Systems (IRDS) by the IEEE, semiconductor node technology is predicted to reach around 0.5 nm by 2037, with transistor gate lengths of 12 nm. Remarkably, the research team demonstrated that the channel width, modulated by the electric field applied from the 1D MTB gate, can be as small as 3.9 nm, exceeding futuristic predictions.

Furthermore, the 1D MTB-based transistor offers advantages in circuit performance. Complex device structures such as FinFET or Gate-All-Around, commonly used for miniaturizing silicon semiconductor devices, suffer from parasitic capacitance, leading to instability in highly integrated circuits. In contrast, the simple structure and extremely narrow gate width of the 1D MTB-based transistor minimize parasitic capacitance.

Director Jo Moon-Ho, head of the Center for Van der Waals Quantum Solids, expressed enthusiasm for the research findings. He stated, "The 1D metallic phase achieved through epitaxial growth is a new material process that can be applied to ultra-miniaturized semiconductor processes. It is expected to become a key technology for developing various low-power, high-performance electronic devices in the future."

This breakthrough in epitaxial growth and the synthesis of metallic 1D mirror twin boundaries opens up new possibilities for the development of ultra-miniaturized 2D semiconductor logic circuits. The research team's work not only contributes to the advancement of semiconductor technology but also demonstrates the potential for material synthesis through precise control of crystal structures.