1. Carlos Andrés Jarro Dr. J. Todd Hastings
Improvement on Pattern Quality Made by Negative-tone Silver Patterning using AFM and Laser-induced Deposition from Liquids
Carlos Andrés Jarro
Dr. J. Todd Hastings
I HAVE BEEN WORKING IN DR HASTINGS LAB FOR 3 YEARS ON SILVER NANOPARTICLES FORMATION, DEPOSITION, AND APPLICATIONS.

2. Fabrication of silver nanoparticles is not new
Fabrication of silver nanoparticles is not new. The silver institute says that the first published paper on fabrication of silver nanoparticles in solution dates from That is 124 years worth of research and we still try to find ways to form, shape, and control the synthesis of silver nanoparticles today.

3. Previous Work In Solution On Substrates
Chemically synthesized
Photo synthesized
On Substrates
Surface-Enhanced Raman Spectroscopy (SERS)
Antibacterial surfaces
Patterning
100nm
Uncoated Coated
Lv, H. Liu, Z. wang, L. Hao, J. Liu, Y. Wang, G. Du, D. Liu, J. Zhan and J. Wang, Polymers for Advanced Technologies, n/a (2008).
Massive amount of research in formation of silver nanoparticles, most of them in solution; using different chemistry (Capping agents, reducing agents, molecules containing silver) and different temperatures.
Change high temperatures for the use of light.
Many researchers form silver NP in solution and then deposit them on substrates but others have formed the NP directly on the substrate.
Mostly for SERS applications, but also antibacterial surfaces, film deposit or patterning.
Y. Sun and Y. Xia, Science 298, (2002).
200nm
H. Jia, W. Xu, J. An, D. Li and B. Zhao, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy 64, 956 (2006).
H. Lu, H. Zhang, X. Yu, S. Zeng, K.-T. Yong and H.- P. Ho, Plasmonics 7, 167 (2011).
Y. Wan, Z. Guo, X. Jiang, K. Fang, X. Lu, Y. Zhang and N. Gu, Journal of colloid and interface science 394, 263 (2013).
B. Xu, Z. Ma, L. Wang, R. Zhang, L. Niu, Z. Y. Yang, Y. Zhang, W. Zheng, B. Zhao, Y. Xu, Q. Chen, H. Xia and H. Sun, Lab on a Chip 11, 3347 (2011).
A. Lachish-Zalait, D. Zbaida, E. Klein and M. Elbaum, Advanced Functional Materials 11, 218 (2001).

4. Agenda Previous Work Hypothesis Experimental Setup
Results and Discussion
Conclusions
Future Work & Applications

5. Previous Work -Experimental Setup
AgNO3
+ Na-citrate
O-ring
Glass slide
532 nm Continuous Wave Laser

6. Previous Work -Silver depositionhv + + e-
Acetone-1,3-dicarboxylate
Carbon
dioxide
1 mM Sodium Citrate + + Ag
1 mM Silver nitrate

7. Agenda Previous Work  Hypothesis Experimental Setup
Results and Discussion
Conclusions
Future Work & Applications

8. Hypothesis -AFM tip introduction Illuminated sharp tip
Plasmonic enhancement
Patterns of silver ONLY where the tip scans
What if we can find an intensity value at which there is no deposition on the substrate but due to the plasmonic enhancement at the tip’s apex there will be deposition below the tip’s location
I. Notingher and A. Elfick, J. Phys. Chem. B 109, (2005).

9. Agenda Previous Work  Hypothesis  Experimental Setup
Results and Discussion
Conclusions
Future Work & Applications

10. Experimental Setup AFM gold coated tip AgNO3 + Na-citrate O-ring
Glass slide
532 nm Continuous Wave Laser

11. Agenda Previous Work  Hypothesis  Experimental Setup 
Results and Discussion
Conclusions
Future Work & Applications

12. Results and Discussion
Intensity
Scan speed
Illumination times
Deposition everywhere EXCEPT where the tip scans
Further deposition suppressed where tip scans

13. Results and Discussion -Negative tone patterning. What shapes?

14. Results and Discussion -Negative tone patterning. How small?
200 nm-250 nm

15. Results and Discussion
Reduce nanoparticles’ size
Shorter illumination times
Improved precursor concentrations
Increase deposition density
Longer illumination times
Coat the glass slide

16. Results and Discussion
Silver Nitrate concentrations
0.1 mM
1 mM
10 mM
Sodium Citrate Concentrations
No deposition Observed
Reacted without illumination
36 nm diameter
0.8% coverage
29 nm diameter
6.7% coverage
43 nm diameter 2.6% coverage
66 nm diameter
13.7% coverage
29 nm diameter
7.1% coverage
29 nm diameter
7.1% coverage
56 nm diameter
3.4% coverage
85 nm diameter
15.3% coverage

17. Results and Discussion
Reduce nanoparticles’ size
Shorter illumination times
Improved precursor concentrations
Increase deposition density
Longer illumination times
Coat the glass slide

18. Results and Discussion -Glass coating with APTES
AminoPropylTriEthoxySilane
APTES is a silane with one amine group and three methyl groups.
In water it reacts replacing the methyl groups with hydroxyl groups, forming ethanol, and adding a hydrogen nucleus to the amine group. This is called a protonized APTES.
Negatively charged citrate adsorbs to the silver nanoparticles coating them with a negative charge and hence being attracted to the APTES coated slide.

19. Results and Discussion -Glass coating with APTES
Comparison of coated and uncoated sample
Without APTES
With APTES
Without APTES:
34% area coverage
in the densest region.
With APTES:
Approximately 100% area coverage.

20. Results and Discussion -Patterning

21. Agenda Previous Work  Hypothesis  Experimental Setup 
Results and Discussion 
Conclusions
Future Work & Applications

22. Conclusions
Developed a technique that allows direct deposition and patterning of silver in one step.
Reduced the patterns width by optimizing the precursor solution to obtain smaller nanoparticles.
Improved the coverage of the films by coating the glass substrate with APTES

23. Agenda Previous Work  Hypothesis  Experimental Setup 
Results and Discussion 
Conclusions 
Future Work & Applications

24. Future Work & Applications
Improve the resolution of the technique to form even narrower patterns
Enhanced tip positioning control
Optimize illumination and AFM parameters (illumination time, scan speed, number of scans)
Continue the refinement of the formation of silver to obtain even smaller nanoparticles
Applications in rapid prototyping
Applications in plasmonic sensing

25. Thank you
CMMI and ECCS