100 KEV ELECTRON-BEAM MODIFICATION OF ALUMINUM AND SILICON IN THE STEM

The high current density 100keV focussed electron probe in a Scanning Transmission Electron Microscope (STEM) can be used to produce bulk and surface displacement damage in aluminium and silicon. In aluminium a stationary electron probe can produce a row of facetted voids which grow inwards from the electron exit surface, each void typically 4nm in diameter and 12-24nm in length, separated by equal distances from one another along the irradiated volume. Scanning the electron probe over an area of silicon at high magnification produces an array of circular cross-section 1.2-1.6nm diameter holes, some connected by shallower channels, growing inwards up to 100nm from the electron exit surface. The holes evolve in crystalline silicon irrespective of surface orientation or doping, but are absent in amorphous material.