Laser optothermal nanobomb eliminates nanobubbles in two-dimensional materials

Apr 09, 2026

Researchers developed a laser optothermal nanobomb method that flattens nanobubbles in 2D materials in 50 milliseconds while preserving optoelectronic properties.

(Nanowerk News) A research team at Tsinghua University has developed an all-optical method to eliminate nanobubbles that form in two-dimensional van der Waals materials during fabrication. The technique, called laser optothermal nanobomb (LOTB), uses focused laser light to flatten defects that compromise chip-scale optoelectronic devices built from 2D films such as transition metal dichalcogenides (TMDs). The work, led by Professors Benfeng Bai and Hong-Bo Sun, was published in Light: Advanced Manufacturing (“Laser optothermal nanobomb for efficient flattening of nanobubbles in van der waals materials”).

Key Findings

TMDs are among the most promising candidates for next-generation semiconductor devices. Yet their practical use is hampered by nanobubbles, tiny trapped pockets typically between 10 nanometers and 1 micrometer across, that form during growth and transfer steps. These defects distort the local dielectric environment and introduce unwanted tensile strain, degrading the performance of any device built on the affected film. Until now, no post-processing technique could remove these bubbles once a 2D film had been fabricated and transferred onto a substrate. The LOTB method works by focusing a continuous-wave laser onto the bubble site to create two distinct thermal zones. In the high-temperature region at the beam center, the TMD film sublimates to open a tiny sacrificial breach. In the surrounding lower-temperature region, liquid trapped inside the bubble vaporizes. The pressure difference between the bubble interior and exterior then forces the gas out through the breach, pulling the film flat in roughly 50 milliseconds. The process leaves the material’s intrinsic optoelectronic characteristics intact. “Our study not only reveals the formation dynamics of nanobubbles and explores how they change under laser irradiation, but also provides a novel principle and technique for nanodefect repair in two-dimensional materials,” the scientists note. “This method achieves high-efficiency flattening, non-destructive optoelectronic properties, precise control, and excellent long-term stability. With its high process compatibility under ambient conditions, it offers a reliable solution for defect repair in 2D material-based devices.” Measurements on single-layer molybdenum disulfide (1L-MoS2) films showed that LOTB reduced surface roughness by more than 70%. Nano-photoluminescence and Raman spectroscopy confirmed that the flattened regions retained their original optical quality. To move beyond single-bubble repair, the team developed dual-beam cascaded and multi-shot irradiation strategies. These approaches expand the treatable area and raise processing speed, making the technique suitable for mass production of 2D material devices. “These features give this method outstanding advantages in the mass production of two-dimensional materials and devices. It is expected to play an important role in expanding the application prospects of high-performance 2D material devices in the next-generation semiconductor industry,” the scientists forecast. Because LOTB operates under ambient conditions and requires only standard continuous-wave laser equipment, it can integrate into existing fabrication lines without specialized infrastructure. The method’s combination of millisecond processing speed, verified material preservation, and scalable multi-beam operation addresses a specific bottleneck that has limited the transition of 2D materials from laboratory research to industrial manufacturing.