I did my first postdoc with John Weaver's group at the University of Illinois in Urbana-Champaign. His group uses transmission electron microscopy (TEM) and scanning tunneling microscopy (STM) to investigate the properties of nanometer-sized metallic clusters (Au, Ag, Cu,...) and semiconductor surfaces (Si and GaAs). I used STM to study the surface of silicon and its modification by reactions with halogen gases (Chlorine and Bromine).
The STM is an atomic resolution microscope invented in the mid 80s. For an introduction to STM, look at this guide from TM Microscopes. At the time, we had 2 commercial ultra-high vacuum (UHV) STMs: an AutoProbe VP from Park Scientific Instruments and a STM1 from Omicron NanoTechnology, but controlled with an RHK controller. The vacuum chambers had base pressures in the mid 10-11 Torr range and included tools for LEED, AES, in situ cleaving, heating, thin film deposition, dry etching, and electron modification. Here is an image of the tip/sample junction in the room temperature Omicron STM. Below are STM images I obtained with the STMs. Click the images to see a larger version.
I also performed variable temperature STM experiments with equipment available in the Center for Microanalysis of Materials in the Frederick Seitz Materials Research Laboratory. I worked with Vania Petrova to study silicon surfaces at high and low temperature. Here is a picture of the VT-STM chamber.
- Omicron STM 1 Images of Si(100)-(2x1) in UHV:
50.0 x 50.0nm2 30.0 x 30.0nm2 25.0 x 25.0nm2 Derivative + Topography
25.0 x 25.0nm2
50.0 x 50.0nm2
- AutoProbe VP Images of GaAs(110) in UHV:
20.0 x 20.0nm2 350.0 x 350.0nm2 25.0 x 25.0nm2 12.0 x 12.0nm2
|A Few Research Links:||A Few Vendors:|
John Weaver's Homepage
Laboratorio De Nuevas Microscopías
Nanophysics at Purdue University
The Lagally Group
Annabella Selloni's Homepage
Cees Dekker's Group
The IBM Almaden STM Site
Omicron Vakuumphysik GmbH
di (Bought by Veeco)
Park Scientific Instr. (Bought by TM-Microscopes) (Bought by Veeco)