Scalable nanostructuring on polymer by a SiC stamp: optical and wetting effects Aikaterini Argyraki, Weifang Lu, Paul Michael Petersen, Haiyan Ou Department of Photonics Engineering, Technical University of Denmark My talk for today is entitled : Scalable nanostructuring on polymer by a SiC stamp. Optical and wetting properties. As you might be able to see from the title I will discuss 4 points of interest. 1)The nano fabrication of the stamp. 2) the replication of the nanostructures on the polymer. 3) the optical effects due to nanostructuring and 4) the wetting effects after nanostructuring.

Outline Motivation - Wafer-Scale nanostructuring of SiC stamp - Replication of nanostructures on a polymer surface -Optical effects -Wetting properties Conclusions Fabrication Characterization Answer to questions like :Why is it important to be able to nanostructure on large interfaces. Why on polymer? See the farication process :nano engineering part Characterization: what macroscopic properties can we achieve?Conclude Technical University of Denmark Aikaterini Argyraki

Motivation Push performance of devices towards their optimum limits by controlable fabrication of interfaces at the nanoscopic level. Polymer materials gain interest both as semiconductors and conductors due to their low cost. Cell proliferation. Bactericidal attachment and survival. Photoluminescence. Absorbance. Technical University of Denmark Aikaterini Argyraki

and….nanopattern definition must be: Rapid Low-cost Prerequisites Fabrication of nanostructures that result in macroscale effects with reproducibility ! and….nanopattern definition must be: Rapid Low-cost Applicable on wafer scale-high throughput Technical University of Denmark Aikaterini Argyraki

SiC nanostructuring: summary table Type of structures Method Average Reflectance (%) Luminecence enhancement (from 10 to 80 degrees) Periodic E-beam 1,01 104% Semi-periodic Self-assembly 1,62 67% Tradeoff between low cost and performance. Low cost method had issues of compatibility with equipment for wafer processing due to the Au mask. *Reference: Y. Ou, et al., Optics Express 20, 7, 2012. Y. Ou, et al., Opt. Lett. 37, 18, 2012. Periodic Semi-periodic 5 Technical University of Denmark Aikaterini Argyraki

A cost effective method for SiC aperiodic nanostructuring Reactive ion etching. High-energy ions from the plasma attack the wafer . Technical University of Denmark Aikaterini Argyraki 6

Combinatory masking 200nm 7 Technical University of Denmark Aikaterini Argyraki 7

Ramping: RIE conditions+ Al thickness *Reference: Measurement goniometer *Reference: A. Argyraki et al., Optical Materials Express 8(3) 2013. 04-06-2013

Fabrication of different nanotopographies Color texture changes due to nanostructuring 9

Optical properties: Reflection, Transmission Average 25% Average 37% Average 33% Average 5% Average 13% Average 0,5% Integrating sphere. Technical University of Denmark Aikaterini Argyraki 10

Scalability Technical University of Denmark Aikaterini Argyraki 11

Summary table Type of structures Method Average Reflectance (%) Luminecence enhancement (from 10 to 80 degrees) Periodic E-beam 1,01 104% Semi-periodic Self-assembly* 1,62 67% Stochastic Combinatory masking 0,50 165% *Reference: Ou, H., Advances in wide bandgap SiC for optoelectronics, The European Physical Journal B Periodic Semi-periodic Stochastic 12 Technical University of Denmark Aikaterini Argyraki

Replication of nanostructures on polymer Process flow Technical University of Denmark Aikaterini Argyraki 13

Ni shim: generation Technical University of Denmark Aikaterini Argyraki 14

Nanostructured polymer surface Good replication of structures but with more rounded edges. Technical University of Denmark Aikaterini Argyraki 15

Color textures after nanostructuring on polymer A thin Al layer (~40nm) 16

Optical and wetting properties after nanostructuring on polymer Average 88% Average 11% Average 85% Average 5% Average 33% Average 3% 68 degrees 123 degrees 75 degrees 132 degrees Polymer-bare Polymer-nano Al coated-bare Al coated-nano

Conclusions Demonstrated 2 inch wafer nanostructuring on polymer by a SiC stamp Color texture and transmitance of SiC surface was controled by nanotopography applied Color texture and reflectance of polymer surface was significantly altered by nanostructuring and additional deposition of a thin Al layer Wetting properties of surfaces shifted after nanostructuring from hydrophilic to hydrophobic Technical University of Denmark Aikaterini Argyraki 18

Acknowledgment Weifang Lu Yiyu Ou Paul Michael Petersen Haiyan Ou 19 Assistance. Weifang Lu Yiyu Ou Paul Michael Petersen Haiyan Ou Technical University of Denmark Aikaterini Argyraki 19

Thank you for your attention Contact info: aikar@fotonik.dtu.dk Technical University of Denmark Aikaterini Argyraki 20