Microscopie à force atomique: Le mode noncontact

Transcription

1 Microscopie à force atomique: Le mode noncontact Clemens Barth CRMCN-CNRS, Campus de Lumny, Case 913, Marseille Cedex09, France La Londe les Maures (France) /03/2007

2 L'atelier NC-AFM Jeudi :30 17:45 1. Introduction C. Barth 18:15 19:15 2a. Partie I - approche théorétique et instrumental S. Gauthier 21:00 22:00 2b. Partie I - approche théorétique et instrumental S. Gauthier Vendredi :15 10:00 3. Partie II - applications et extensions L. Nony 10:30 11:45 4. Partie III - Tuning fork AFM L. Pham Van 11:45 12:00 5. Partie IV - Résumé C. Barth

3 L'aide A partir du 24/03/2008 Liste des orateurs Liste des publications Liste des personnes les plus engagées dans le domaine NC-AFM Liste des revendeurs d'afm Les présentations des intervenants seront également disponibles au format électronique.

4 Le Menu Partie I: Présentation historique et le principe du NC-AFM Émergence du NC-AFM - Review de Franz Giessibl [Rev. Mod. Phys. 75 (2003) 1] NC-AFM vs Contact AFM Contexte international et en France Partie II: Vue d'ensemble : Exemples de ce qui peut être fait en NC-AFM Imagerie des surfaces planes et propres (UHV) - Surfaces des métaux, semi-conducteurs, isolants - Résolution atomique - Spectroscopie de force (à basse température) Imagerie de nano-objets: molécules, nano-agrégats métalliques Sonde de Kelvin

5 Part I Why Noncontact Atomic Force Microscopy? (NC-AFM)

6 STM: Atomic scale imaging & manipulation Nobel price Palladium atoms on a Pd surface in UHV G. Binning H. Roher Tunneling Binnig, Rohrer, Gerber, Weibel, APL 40 (1982) x cited STM images Binnig, Rohrer, Gerber, Weibel, PRL 49 (1982) x cited STM images Binnig, Rohrer, HPActa 55 (1982) x cited 7x7 Si(111) Binnig, Rohrer, Gerber, Weibel, PRL 50 (1983) x cited Eigler et al., Science 262 (1993) ISI Web of Science, 05/03/2008 Problem: The STM requires electrical conduction of the sample!!

7 Imaging insulators with the STM? Solution: Growth of a thin insulating film on a metal surface Insulator Metal Ag, Cu, Mo Si, W, etc. MgO, NaCl, KBr, SrTiO 3, Al 2 O 3, CeO 2 Thickness of some monolayers (~Å) Tunneling through the film Since the end of the 90 s, it has become a favored surface preparation technique for STM

8 STM imaging on thin insulator films MgO(001)/Ag(001) Oxides as supports for clusters Pt/TiO2(110) Diebold et al., Phys. Rev. Lett. 84 (2000) Schneider et al., Phys. Rev. Lett. 87 (2001) Al2O3/Ni3Al(111) 10nm Henry et al., Nanotechnology 17 (2006) Au/Pd on Al2O3 thin films Henry et al., Nanotechnology 17 (2006) Pd/SrTiO2(001) Castell et al., Phys. Rev. B 72 (2005)

9 What about bulk insulators? Atomic force microscopy

10 The introduction of the AFM ! ~10 years! Atomic resolution on Si(111) 7x7 Giessibl Invention of the STM Atomic resolution on Si(111) 7x7 1) Nobel price for Binnig and Roher (and Ruska) 2) Introduction of the AFM Binnig,Quate and Gerber NC-AFM: True atomic res. on NaCl(001) Meyer, Güntherodt Do we get atomic resolution also on an insulator surface? Binnig, Quate and Gerber, Phys. Rev. Lett. 56 (1986) 930 at Stanford University / IBM

11 AFM: Atomic Force Microscopy SFM: : Scanning Force Microscopy 1986 Invention of the AFM by G. Binnig, C.F. Quate and Ch. Gerber Stanford University / IBM Phys. Rev. Lett. 56 (1986) x cited (05/03/08)! Cantilever Tip F No restriction on type of material Imaging insulating surfaces is now possible

12 The (UHV) Scanning Force microscope Laser Tip Sample Detector (PSD) Laser beam L ~ 5cm Mirror Mirror Cantilever Other detection techniques Interferometer Piezoresistive cantilevers Sample

13 AFM: : Introduction and true atomic resolution LiF(001) Invention of the STM Atomic resolution on Si(111) 7x7 C-AFM: Atomic periodicity LiF(001) Meyer, Güntherodt Nobel price for Binnig and Roher (and Ruska) + Introduction of the AFM Binnig, Quate and Gerber Meyer, Güntherodt et al., Z. Phys. B 79 (1990) 34 Si(111) 7x7 Meyer, Güntherodt et al., Z. Phys. B 93 (1994) 267

14 Contact AFM: The tip-surface contact Force-distance curve F N 3 Contact area R 4 z (Piezo displacement) a Incident 2 occurs, if k < max(- df ts /dz) Jump-into-contact 3-4: Capillary forces (in air) 2a = 2 * E * (F * R) 1/3 F: Force, E: Young Module Air : 5-100nm UHV : 1-10nm Tip is always in contact with the surface!

15 Contact AFM: Imaging the atomic periodicity Au / Mica (001) Problem: Multiple atom-atom interaction Exchange of particles between tip and surface - on reactive surfaces like Si(111) 7x7 - on ionic surfaces (NaCl) A. L. Shluger et al., J.Phys.: Con. Matt. 11 (1999) R295 L. Howald et al., Phys. Rev. B 49 (1994) 5651 (111) S. Ferrero, A. Piednoir, C.R.Henry, Nanoletters 1 (2001) 227

16 AFM: : Introduction of the noncontact mode f = f-f 0 Invention of the STM Atomic resolution on Si(111) 7x7 C-AFM: Atomic periodicity LiF(001) Nobel price for Binnig and Roher + Introduction of the AFM "Introduction" of the NC-AFM Albrecht, Grütter, Horne, and Rugar No jump-into-contact In UHV: High Q-factor High sensitivity Atomic resolution Note that the first dynamic (STM) tip was already realized in 1986 by Dürig, Gimzewski and Pohl