Laser writing of electronic circuitry in thin film molybdenum disulfide: A transformative manufacturing approach

Abstract

Electronic circuits, the backbone of modern electronic devices, require precise integration of conducting, insulating, and semiconducting materials in two- and three-dimensional space to control the flow of electric current. Alternative strategies to pattern these materials outside of a cleanroom environment, such as additive manufacturing, have enabled rapid prototyping and eliminated design constraints imposed by traditional fabrication. In this work, a transformative manufacturing approach using laser processing is implemented to directly realize conducting, insulating, and semiconducting phases within an amorphous molybdenum disulfide thin film precursor. This is achieved by varying the incident visible (514 nm) laser intensity and raster-scanning the thin film a-MoS2 sample (900 nm thick) at different speeds for micro-scale control of the crystallization and reaction kinetics. The overall result is the transformation of select regions of the a-MoS2 film into MoO2, MoO3, and 2H-MoS2 phases, exhibiting conducting, insulating, and semiconducting properties, respectively. A mechanism for this precursor transformation based on crystallization and oxidation is developed using a thermal model paired with a description of the reaction kinetics. Finally, by engineering the architecture of the three crystalline phases, electrical devices such as a resistor, capacitor, and chemical sensor were laser-written directly within the precursor film, representing an entirely transformative manufacturing approach for the fabrication of electronic circuitry.