AVS 51st International Symposium
    Nanometer-scale Science and Technology Thursday Sessions
       Session NS1-ThA

Paper NS1-ThA6
High Resolution Structural and Chemical Information: A Combined STM, SEM and SAM Analysis of Ag Nanocrystallites on Si

Thursday, November 18, 2004, 3:40 pm, Room 213C

Session: Nanoscale Imaging
Presenter: J. Westermann, OMICRON NanoTechnology GmbH, Germany
Authors: J. Westermann, OMICRON NanoTechnology GmbH, Germany
M. Maier, OMICRON NanoTechnology GmbH, Germany
J. Poppensieker, OMICRON NanoTechnology GmbH, Germany
G. Schaefer, OMICRON NanoTechnology GmbH, Germany
Correspondent: Click to Email
For the analysis of nanostructured materials it is of crucial importance to be able to characterise not only structural properties of the material, but also determine chemical composition, as well as electronic and magnetic properties of individual nanostructures. To accomplish this, we have combined a high resolution SEM column with an STM under true UHV conditions with extension possibilities for AFM, SEMPA, FIB, and EBL. This enables in situ SEM and STM imaging to study the sample topography from mm down to 10 pm scale on the same sample spot. Using the electron column as an excitation source for Auger, chemical analysis is possible with sub 10 nm resolution. STM related techniques like STS allow the characterisation of the electronic structure and magnetic imaging using spin polarised STM. Besides the observation of sample properties, the STM+SEM combination also offers unique possibilities for sample modification on the nanoscale, offering both electron beam lithography and STM manipulation under SEM control. Using Ag nanocrystals on Si(111), we demonstrate the capabilities of this approach. The samples were prepared by evaporation of Ag on a clean Si (111) substrate at elevated temperatures. We show SEM and SAM images with a resolution down to 3 nm (SEM), and 10 nm (SAM) respecively allowing for chemical analysis with ultimate resolution. We demonstrate the importance of SEM to select areas of interest, and subsequently position the STM tip to image these areas. STM images with atomic resolution show the surface structure and reconstructions on both the silver crystals and the silicon substrate. The latter shows a @sr@3x@sr@3 reconstruction induced by the silver.