Homemade STM

STM Research

My research group uses scanning probe microscopy (SPM) extensively. SPM includes a set of tools (scanning tunneling, atomic force, kelvin probe force, etc. microscopies (STM, AFM, KPFM) that can look closely at a material's surface. SPM is particularl useful at the nanoscale, where surface properties can dominate the properties of a material. Several of the microscopes my group uses are in the Boise State Surface Science Laboratory.

As a graduate student in Ron Reifenberger's group at Purdue University, learned about atomic force microscopy (AFM) and scanning tunneling microcsopy (STM), as well as Field Emission and Field Ion Microscopies (FEM and FIM). I fell in love with being able to see materials at the nano and atomic scales. You can still see some of the old images we obtained here and here.

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). A good primer on STM is at the nanoHUB.

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.

STM Images