Fabrication and STEM/EELS measurements of nanometer-scale silicon tips andfilaments

We present a series of scanning transmission electron microscopy and electr on energy-loss spectroscopy (EELS) measurements of nanometer-scale single-c rystal silicon tips and filaments. The tips and filaments are of a type tha t we are currently integrating into microelectromechanical systems. The EEL S measurements reveal a number of nanometer-scale effects, some of which ha ve already been reported in the literature for other systems. These effects include apparent upward shifts in the energies, widths, and interaction cr oss sections of the plasmons. in addition, we report a sharp peak at 5 eV, which we are identifying as an interband transition in the silicon. We prov ide theoretical explanations of the characteristics of this new peak, inclu ding an explanation of its failure to appear at any but the smallest sample diameters. Finally, we extend the theory already present in the literature with a finite-element model of EELS for nonpenetrating electrons in an arb itrary geometry. [S0163-1829(99)10131-0].