BALLISTIC ELECTRON-EMISSION MICROSCOPY INVESTIGATION OF SIGE NANOSTRUCTURES FABRICATED USING REACTIVE-ION ETCHING

We have applied ballistic electron emission microscopy (BEEM) to microfabricated semiconductor structures in order to study the damage effects of dry etching. Structures were defined in Si0.92Ge0.08 using electron-beam lithography and reactive-ion etching. A gold Schottky contact was deposited on the surface, and the transport properties of the metal-semiconductor interface were then characterized using BEEM. BEEM current versus voltage spectra were fit with a two parameter model to determine the local Schottky barrier heights and transmission probabilities of adjacent etched and unetched regions. BEEM enables us to nondestructively examine the electrical nature of the etched surface with nanometer resolution. The results show a lower average barrier height in the etched regions compared to that of the unetched regions, consistent with macroscopic results. This technique also enables us to observe the distribution of local barrier heights with microscopic resolution much higher than conventional techniques.