The uniqueness of using lasers lies in the ability to locally vary the intensity of light and exposure time, which precisely modifies the crystal structure and chemistry of the thin film in a location as small as one micrometer (much smaller than the width of a human hair). The amorphous film is then readily transformed into three different materials: semiconducting crystalline molybdenum disulfide, conducting molybdenum dioxide, and insulating molybdenum trioxide all with the precise conditions.
Laser writing of electronics utilizing a green laser and custom environmental chamber setup. U.S. AIR FORCE PHOTO/SPENCER DEER
“Alternative strategies to pattern these materials outside of a cleanroom environment, have enabled rapid prototyping and eliminated design constraints imposed by traditional fabrication,” said Dr. Nicholas Glavin, materials scientist from the Air Force Research Laboratory. “Future development could see fully user-customized electronics.”
By modifying the laser pattern, individual electronic circuits can be designed on the fly with nearly complete freedom within the bounds of the manufacturing process. This is in contrast to traditional circuit design using thin film cleanroom processes, which can restrict reconfigurability, requiring expensive start-up equipment and a multitude of steps to complete.
“By engineering the architecture of the three different 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,” said Dr. Drake Austin, research scientist from UES Inc.
Further optimization of film uniformity utilizing different laser sources and profiles is expected to result in highly controllable properties for future electronics and sensor devices. Additionally, exploring the transformative manufacturing technique utilizing optical sources to include flash lamps, parallel laser sources, laser holography and pulsed laser systems will significantly reduce the manufacturing time and increase the throughput and open new potential device architectures.
It is expected that by laser-processing these, or similar materials in active gases, various chemical reactions can be locally induced, possibly with the ability to access other chemistries/structures as well as new reaction intermediates for more complex circuitry.
The transformative manufacturing approach represents another instrument to add to the toolbox for manufacturing of novel electronic materials and devices, where the freedom of design and ease of manufacturing truly puts the user in the driver seat for customizable electronics.
The work was supported by the Air Force Office of Scientific Research. The article in “Materials Today” can be found at https://www.sciencedirect.com/science/article/abs/pii/S1369702120303394 .
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