ChemE Faculty, Ph.D. Student Publish Paper on Scalable Nanofabrication Technique

June 28, 2022

Nanofabrication collageBATON ROUGE, LA – A new paper detailing a scalable nanofabrication technique that vastly improves the precision of periodic nanostructures has been published and selected as an Editor’s Pick in the Journal of Vacuum Science & Technology A. The piece, titled “Better Colloidal Lithography: Tilt-Rotate Evaporation Overcomes the Limits of Plasma Etching,” is by Chemical Engineering Associate Professor Kevin McPeak, Chemical Engineering Professor Michael Benton, and third-year chemical engineering Ph.D. student MaCayla Caso. A montage of images from the work will also appear on the July/August cover of the publication.

The full paper can be read by clicking here.

Colloidal lithography is a promising method for large-area fabrication of nanohole and nanodot arrays with applications in optical biosensing, separations, and magnetic data storage. However, reducing the diameter of the polystyrene sphere mask by plasma etching unavoidably increases their coefficient of variation (CV) and deforms their shape, thereby limiting the pitch-to-hole-diameter ratio of the resulting nanohole array to less than 3:1 and the minimum hole size to 200 nm with a 10% or better CV. 

The paper details that tilt-rotate evaporation colloidal lithography (TRE-CL) breaks the trade-off between hole diameter and polydispersity by leveraging glancing angle evaporation, not plasma etching, to adjust the hole size. TRE-CL allows pitch-to-hole-diameter ratios as high as 7:1 and nanohole diameters down to 60 nm while maintaining a nearly constant CV below 10% and hole circularity above 91%. The research group transfers these hole arrays into ultrathin Si3N4 films to form nearly-monodisperse microsieves for separation applications. Furthermore, it extends TRE-CL to fabricate adhesion-layer-free plasmonic Au nanodot arrays down to 70 nm in diameter with 10% CV.

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