A research team from Xi’an Jiaotong University, led by Xuesong Mei and Jianlei Cui, has made major strides in the field of nanotechnology, according to a recent study published in Engineering.
Image Credit: MeshCube/Shutterstock.com
Creating nanostructures beyond the diffraction limit has long posed a challenge in nanotechnology. Traditional optical lithography is limited by the diffraction barrier, while electron beam lithography is unsuitable for metal nanofilms.
Scanning probe lithography (SPL) offers an alternative, but each SPL technique has specific limitations.
In this study, the researchers developed a laser direct-writing system consisting of a nanosecond laser, optical elements, and an atomic force microscope (AFM), enabling them to focus the laser on the SNOM probe tip to directly write nanostructures on the Au film—without requiring a mask or vacuum conditions.
The team achieved a minimum linewidth of 83.6 nm and a repeatable linewidth of approximately 167.8 ± 6.6 nm on the gold film. They examined factors influencing the feature width, including single-pulse energy and polarization, finding that the heat distribution beneath the SNOM tip varied based on scanning direction.
Elemental analysis using energy dispersive spectrometry (EDS) confirmed that the process involved melting, rather than oxidizing, the gold nanofilm. The localized surface plasmon polaritons (SPPs) produced by the SNOM tip generate a high-temperature spot, acting as a nanoscale energy source for precise nanofabrication.
This method is efficient and cost-effective, holding promise for nanostructure fabrication across various materials and even potential applications in nanolithography and nanowelding.
Xuewen Wang, Xuesong Mei, Hailong Yin, Zhijun Wang, Xiaoqiao He, and Jianlei Cui were the study authors.
Journal Reference:
Wang, X. et. al. (2024) Direct Writing Nanostructures on Au Nano-Film by Laser Irradiating Cantilevered Scanning Near-Field Optical Microscope Tip. Engineering. doi.org/10.1016/j.eng.2024.07.014