1. Nanoscale Imaging of Buried Structures via Scanning Near-Field Ultrasound Holography G. S. Shekhawat and V. P. Dravid, Science, 310, 89(2005). Journal Club Presentation 30/10/06 Onur Basarir

2. Background AFM (Atomic Force Microscopy)

3. AFM Superb spatial resolution, but nothing about subsurface properties.

4. Motivation Near field SPM  Excellent lateral resolution Ultrasound  Non-destructive and depth sensitive Holography  Sensitive to phase

5. 1 - Ultrasonic Force Microscopy O. Kolosov et.al, PRL, 81, 1046 (1998) F. Dinelli,et.al, PRB, 61,13995(2000).

6. 2 – Acoustic Force Microscopy U. Rabe et.al.,Ultrasonics, 38, 430(2000).

7. 3 – Heterodyne Force Microscopy M T Cuberes et al 2000 J. Phys. D: Appl. Phys. 33 2347-2355

8. Drawbacks of these Techniques Contact mode Amplitude measurements

9. Setup

10. Setup for non-contact operation Lock-in f2f2 f1f1 f 2 -f 1

11. Results I Nanostructures 500 nm below the surface

12. Results II

13. Results III

14. Results I V

15. Conclusion Non-invasive: based on acoustic waves Sub-surface: transparent to acoustic waves Nano-scale resolution

16. Contact AFM

17. Non-Contact AFM

18. Tapping Mode AFM