ATOMIC-FORCE AND SCANNING-TUNNELING-MICROSCOPY STUDY OF CURRENT-VOLTAGE PROPERTIES OF TIB2 MICROCONTACTS

Scanning probe microscopy was used to investigate electrical microcont acts in the nanometer range, With the atomic force microscope current flowing through the contact as well as current-voltage characteristics of the contact as a function of the force acting on the contact itsel f were recorded. With the scanning tunneling microscope current-voltag e characteristics and voltage at constant current characteristics were measured as a function of the contact position. From these experiment s we conclude that a TiB2 microcontact can sustain a maximum voltage o f about 0.1-1 V before melting. These results were confirmed by a theo retical model. The implications for the functioning of so-called posit ive temperature coefficient current limiting devices based on filled p olymers is discussed. (C) 1997 American Institute of Physics.