Superhydrophilic Surface by Aluminum-Induced Crystallization of Amorphous Silicon Ken Kollias Pennsylvania State University Dr. Min Zou Mechanical Engineering Dept. Dr. Li Cai Electrical Engineering Dept.

Objective To study the wettability of textured surfaces on glass using Aluminum-Induced Crystallization (AIC) of amorphous silicon (a-Si) technique. To study the stability of superhydrophilic surfaces. To convert superhydrophilic surface to superhydrophobic.

Outline Introduction Process –AIC of a-Si –Characterization Results Conclusion

Introduction AIC of a-Si –Overview Reasons for Studying –Wenzel’s Equation –Glass naturally hydrophilic

Process Glass Substrate –a-Si deposition using PECVD Thin film with appropriate pressure, time, temp, gas flow –Al deposition using Thermal Evaporator Thin film with appropriate pressure and deposition rate –Annealing Temp= T1, T2, and T3 Time= 5 and 10 minutes –Al Etch

Characterization Wettability –Water Contact Angle (WCA) Crystallization –X-Ray Diffraction (XRD) Topography –Environmental Scanning Electron Microscopy (ESEM) Image taken from

Results Wettability

T3 after 192 hrs

t = 0.12 sec t = 0.5 sec t = 0 sec

Results Crystallization

Results Topography (of superhydrophilic sample) Change In Plans mag=1,000x; bar=20ummag=20,000x; bar=1um

Results Switch to Superhydrophobic (WCA = o )

Results Discussion –Why is this study significant? Other Research Groups –Future research Reason for stability of Superhydrophilicity Superhydrophilic-superhydrophobic pattern Reproducible?  Real World Applications

Conclusion A highly stable superhydrophilic surface, with the capability of converting to superhydrophobic, was created using AIC of a- Si on glass. There is an array of potential applications for this finding.

Acknowledgements Ying Song and Hengyu Wang. National Science Foundation (NSF) through REU Site and Nanoscale Exploratory Research Programs. Equipment support from Oak Ridge Associated Universities through the Ralph E. Powe Junior Faculty Enhancement Award.

Questions? or Comments.

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