Tsinghua University Engineers Develop Laser Optothermal Nanobomb To Repair Nanodefects In Two Dimensional Semiconductors

Tsinghua University researchers introduce the LOTB method, using lasers to eliminate nanobubbles in 2D materials without damaging optoelectronic properties.

By: AXL Media

Published: Apr 9, 2026, 9:19 AM EDT

Source: Information for this report was sourced from EurekAlert!

Overcoming Structural Obstacles In Next Generation Optoelectronics

Two dimensional van der Waals materials, particularly transition metal dichalcogenides, are increasingly recognized as vital components for the future of chip scale electronic devices. However, the manufacturing and transfer of these ultra thin films often result in the formation of nanobubbles, which range in size from 10 nanometers to 1 micrometer. These tiny defects are highly detrimental because they alter the local dielectric environment and introduce unwanted tensile strain, which can degrade the performance of the final device. Until recently, there has been no effective post processing method to eliminate these bubbles once the materials are transferred. A new study published in Light: Advanced Manufacturing introduces a breakthrough solution to this persistent obstacle in semiconductor fabrication.

The Mechanics Of The Laser Optothermal Nanobomb

The researchers from Tsinghua University developed a technique known as the Laser Optothermal Nanobomb, or LOTB, which utilizes a focused continuous wave laser to repair these surface defects. The process operates in three distinct stages, beginning with the focused laser creating a high temperature field that sublimates a microscopic portion of the 2D film to form a sacrificial breach. Simultaneously, a surrounding low temperature field vaporizes the liquid trapped inside the nanobubble. This creates a significant pressure difference that forces the gaseous inclusions out through the breach, effectively flattening the film in approximately 50 milliseconds. This rapid intervention allows for the restoration of the material's structural integrity with extreme precision.

Validated Efficiency and Material Integrity

The effectiveness of the LOTB method was demonstrated on single layer molybdenum disulfide films, where it successfully reduced surface roughness by more than 70%. To ensure that the repair process did not damage the intrinsic properties of the semiconductor, the team utilized nano photoluminescence and Raman spectroscopy for validation. The results confirmed that the laser treatment flattens the nanobubbles while keeping the optoelectronic characteristics of the material intact. According to the scientists, this non destructive nature is a critical advantage, as it allows for the repair of devices after they have already been co...