Domestic researchers have succeeded in solving the biggest drawback of next-generation semiconductor materials. They expect to accelerate the implementation speed of ultra-low-power semiconductors.
The joint research team led by Professor Kwon Ji-min of the Ulsan National Institute of Science and Technology and Professor Noh Yong-young of Pohang University of Science and Technology (POSTECH) announced on the 30th that they developed a technology to remove defects in molybdenum disulfide, a next-generation semiconductor material, at 200 degrees Celsius.
Molybdenum disulfide has recently attracted attention as a low-power semiconductor material that increases the integration density of semiconductor chips and minimizes leakage current, thereby eliminating heat generation. However, the defects that occur when integrating molybdenum disulfide into chips remain a problem that needs to be solved.
During the deposition of molybdenum disulfide, defects occur as sulfur atoms leave gaps where they should be, disrupting the atomic ratio of sulfur to molybdenum. These defects impede the flow of electrons. To ensure semiconductor performance and durability, it is necessary to fill the defects and restore the material to a state close to its theoretical atomic ratio.
High-temperature processes can minimize defects; however, in this case, there is a possibility that silicon, the key material of semiconductors, could be damaged by heat. It is necessary to develop a process that minimizes defects in molybdenum disulfide at low temperatures where silicon is not damaged.
The research team filled the defects at 200 degrees Celsius using a substance called pentafluorobenzenethiol (PFBT), restoring the atomic ratio of molybdenum to sulfur in molybdenum disulfide from 1:2 to approximately 1:98.
Pentafluorobenzenethiol plays a role in inserting sulfur into the defect areas of molybdenum disulfide, allowing sulfur to bond with molybdenum disulfide. The research team confirmed through molecular dynamics simulations that this chemical reaction is possible. Additionally, X-ray spectroscopy analysis indicated that actual sulfur vacancies were filled at low temperatures.
Transistors made from defect-free molybdenum disulfide showed a 2.5 times improvement in charge mobility compared to those with defects. The faster the charge moves, the quicker the operating speed. The indicator of power consumption, known as the 'subthreshold swing value,' also decreased by about 40%.
Professor Kwon Ji-min noted, "The sulfur defects that occur during the process are a significant issue in nanoscale semiconductor devices," and added, "Through the low-temperature sulfur defect recovery technology, we plan to expand research not only on molybdenum disulfide but also on defect recovery and interface property improvement for various next-generation semiconductor materials."
The research findings were introduced in the international journal 'ACS Nano' on the 18th of last month.
References
ACS Nano (2025), DOI: https://doi.org/10.1021/acsnano.4c12927