A scanning tunneling microscope for use in the philips EM400 electron microscope in the reflection mode

Abstract

A scanning tunneling microscope (STM) has been built in the form of a side-entry specimen holder for the Philips EM400T (9mm pole piece gap). The instrument is intended to provide STM and Reflection Electron Microscope (REM) images of the same region, possibly simultaneously (STM operation with tunneling gaps of up to l.5nm is possible while REM resolution is about 0.9nm). The purpose is to study the basic physics of the STM. The great sensitivity of REM diffraction-contrast imaging to strain will be used to determine if strains, or other surface modifications, accompany tunneling on graphite and gold. Figure 1 shows a typical REM image of the GaP[110] surface obtained on the EM400.Figure 2 shows a schematic diagram of the STM while figure 3 shows the completed device, now undergoing trials. A single tube scanner is used5, as in certain stereo record- player cartridges.