Rapid In-Situ Synthesis and Patterning of Edge-Unsaturated MoS2 by Femtosecond Laser-Induced Photo-Chemical Reaction

Molybdenum disulfide (MoS2) is a representative transition metal sulfide that is widely used in gas and biological detection, energy storage, and integrated electronic devices due to its unique optoelectrical and chemical characteristics. To advance toward the miniaturization and on-chip integration of functional devices, it is strategically important to develop a high-precision and cost-effective method for the synthesis and integration of MoS2 patterns and functional devices. Traditional methods require multiple steps and time-consuming processes such as material synthesis, transfer, and photolithography to fabricate MoS2 patterns at the desired region on the substrate, significantly increasing the difficulty of manufacturing micro/nanodevices. In this work, we propose a single-step femtosecond laser-induced photochemical method which can realize the fabrication of arbitrary two-dimensional edge-unsaturated MoS2 patterns with high efficiency in microscale. Based on this method, MoS2 can be synthesized at a rate of 150 mu m/s, 2 orders of magnitude faster than existing laser-based thermal decomposition methods without sacrificing the resolution and quality. The morphology and roughness of the MoS2 pattern can be controlled by adjusting the laser parameters. Furthermore, the femtosecond laser direct writing (FLDW) method was used to fabricate microscale MoS2-based gas detectors that can detect a variety of toxic gases with high sensitivity up to 0.5 ppm at room temperature. This FLDW method is not only applicable to the fabrication of high-precision MoS2 patterns and integrated functional devices, it also provides an effective route for the development of other micro/nanodevices based on a broad range of transition metal sulfides and other functional materials.

Automated summary

Molybdenum disulfide (MoS2) is widely used in various applications due to its unique optoelectrical and chemical characteristics. In this work, a single-step femtosecond laser-induced photochemical method is proposed for the fabrication of microscale MoS2 patterns with high efficiency. The method enables the synthesis of MoS2 at a rate 2 orders of magnitude faster than existing methods, while maintaining resolution and quality. Additionally, the method is demonstrated for the fabrication of high-sensitivity MoS2-based gas detectors. The proposed method not only offers a cost-effective and precise approach for MoS2 patterns and devices, but also provides potential for other transition metal sulfides and functional materials.