Description: Electrical conductance has been measured in-situ in two dimensions in the Ag/Si(111) system as a function of incident adatom flux rate with a 4-probe method. A conductance study in a 3-D conical structure was also made using field emission. For the 2-D study, the origin of conduction is still unclear, as transport by percolating Ag clusters and conduction through the substrate lvia electrons from the film have both been suggested. Experiments varying the flux rate were conducted to decide between the two. Smoother films are expected at lower growth rates which would result in faster drops in the 4-probe voltage; however the 4-probe voltage vs deposition time for various flux rates collapse into a universal curve which indicates that the morphology is not relevant and supports through the substrate. In the 3-D conductance study, a single, lateral micromachined W protrusion on a silica substrate is examined to identify the factors controlling emission in micromachined structures. The I-V characteristics and emission pattern indicate that miniprotrusions of a few hundred Angstroms, much smaller than the nominal radius of the tip, exist on the tip and are responsible for the emission. Adsorption-desorption events from the background environment are the cause of large fluctuations in the emitting current. Comparison of the emission of a single tip to gated arrays suggest that only a fraction of the tips in the array are emitting.
Date: June 19, 1995
Creator: Kimberlin, K.
Partner: UNT Libraries Government Documents Department