Laser Nanolithography Could Improve Nanomaterials

Laser nanolithography shows potential for improving nanomaterials for electronic and optoelectronic components. Research teams at the National University of Singapore, led by professor Dr. Sow Chorng Haur, used similar techniques to alter the optical properties of a film of molybdenum disulfide (MoS₂) and an array of mesoporous silicon nanowires.

Collaborating with researchers from Hong Kong Baptist University, one team generated greenish-blue photoluminescence by fast-scanning a focused green (532 nm) laser beam with power of 5 to 105 mW over a nanowire array.

Micropatterns etched in mesoporous silicon nanowire arrays were invisible under a bright-field optical microscope, as depicted by (a) and (c), but visible under fluorescence microscopy, as depicted by (b) and (d). Courtesy of the National University of Singapore.

The technique was also used to create micropatterns that were invisible under a bright-field optical microscope but visible under a fluorescence microscope.

Using an optical microscope-focused laser beam, the Singapore researchers created microdomains with well-defined structures and controlled thickness on a 2-D film of MoS₂, a transition metal dichalcogenide compound. They said the process increased the film’s electrical conductivity by a factor of 10 and its photoconductivity by a factor of five, allowing them to create photodetectors with improved performance.

The approach is simple and low-cost, the researchers said, and its selectivity has advantages over other techniques that modify films in their entirety.

The work was published in ACS Nano (doi: 10.1021/nn501821z) and Scientific Reports (doi:10.1038/srep04940).

For more information, visit www.nus.edu.sg.