Processing 'Atomic-Scale' 2D Semiconductors with Optical Welding

Research Team Including Dr. Kim Hyunwoo of Korea Research Institute of Chemical Technology
Potential Applications in High-Capacity Semiconductor Memory and More

When a laser beam is emitted, the indium nanoparticles (the round particles in the picture) beneath the thin film melt and fuse with the thin film above, causing the surface of the thin-film semiconductor to be patterned and form undulations. Image courtesy of Korea Research Institute of Chemical Technology.

[Asia Economy Reporter Kim Bong-su] A next-generation semiconductor technology that processes two-dimensional semiconductors made of thin atomic layers by soldering them with light has been developed. It is expected to be utilized in high-capacity semiconductor memory, transparent flexible displays, wearable bio sensors, and more.

The Korea Research Institute of Chemical Technology announced on the 21st that Dr. Kim Hyun-woo, in collaboration with Dr. Shin Chae-ho from the Korea Research Institute of Standards and Science and Professor Kim Tae-wan from Jeonbuk National University, developed a processing technology that patterns two-dimensional thin-film semiconductors by irradiating laser light like soldering. This technology can pattern desired locations almost in real-time within seconds without damaging the thin-film semiconductor, making its application potential very high.

Two-dimensional thin-film semiconductors have advantages such as thin thickness like graphene, transparency, and flexibility, but unlike graphene, they exhibit semiconductor properties. Since their first discovery in 2010, they have attracted attention as next-generation display, optical sensor devices, and semiconductor devices. To utilize two-dimensional thin-film semiconductors as semiconductor devices, a technology to create patterns and circuits on the surface, that is, real-time patterning processing technology, is necessary. For semiconductor materials to be applied in products, it is essential to activate or control electron movement. Therefore, patterning processing technology that can adjust the electron activity energy range (bandgap) by location is indispensable.

However, two-dimensional thin-film semiconductors have a limitation in that they are very thin, about an atomic layer (monolayer thickness ~0.62 nm), making them prone to damage. Conventional semiconductor processing technologies such as thermal processing, ion implantation, and plasma pose a risk of damaging the thin-film surface. Additionally, extra costs and processes are required to pattern desired locations. The processing time can extend from several minutes to hours, resulting in reduced productivity.

The research team placed indium nanoparticles under the two-dimensional thin-film semiconductor and irradiated light of a specific intensity. The light melts the indium nanoparticles without affecting the semiconductor material. The melted indium nanoparticles pull the semiconductor material above them, causing them to stick together. At this time, the semiconductor surface is indented, forming a curved structure, that is, a pattern. The patterned area changes the electron activity energy range (bandgap), partially altering the material's properties. The surface structure of the two-dimensional thin-film semiconductor processed by optical soldering can interact with light, making it applicable to next-generation photodetectors, bio sensors, and more. In particular, the surface structure varies depending on the position, intensity, and irradiation time of the light, allowing diverse processing to achieve desired properties.

This research result was published in September this year in the international journal on optical science and materials, ‘Advanced Optical Materials’ (Impact factor: 10.05).

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